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+/*
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+ * Copyright (C) 2015 Michael Brown <mbrown@fensystems.co.uk>.
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+ *
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+ * This program is free software; you can redistribute it and/or
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+ * modify it under the terms of the GNU General Public License as
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+ * published by the Free Software Foundation; either version 2 of the
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+ * License, or (at your option) any later version.
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+ *
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+ * This program is distributed in the hope that it will be useful, but
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+ * WITHOUT ANY WARRANTY; without even the implied warranty of
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+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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+ * General Public License for more details.
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+ *
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+ * You should have received a copy of the GNU General Public License
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+ * along with this program; if not, write to the Free Software
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+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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+ * 02110-1301, USA.
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+ */
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+
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+FILE_LICENCE ( GPL2_OR_LATER );
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+
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+/****************************************************************************
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+ *
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+ * This file provides the decompress() and decompress16() functions
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+ * which can be called in order to decompress an LZMA-compressed
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+ * image. The code is modelled on the public-domain "XZ Embedded"
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+ * implementation as used by the Linux kernel. Symbol names are
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+ * chosen to match the XZ Embedded implementation where possible, for
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+ * ease of reference.
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+ *
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+ * This code is optimised for size rather than speed, since the amount
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+ * of data to be decompressed is trivially small by modern standards.
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+ *
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+ * The same basic assembly code is used to compile both decompress()
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+ * and decompress16().
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+ *
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+ * Note that these functions require large amounts of stack space.
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+ *
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+ ****************************************************************************
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+ */
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+
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+ .text
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+ .arch i586
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+ .section ".prefix.lib", "ax", @progbits
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+
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+#ifdef CODE16
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+#define ADDR16
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+#define ADDR32 addr32
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+#define decompress decompress16
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+ .code16
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+#else /* CODE16 */
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+#define ADDR16 addr16
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+#define ADDR32
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+ .code32
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+#endif /* CODE16 */
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+
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+/****************************************************************************
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+ * Debugging (via 0xe9 debug port)
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+ ****************************************************************************
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+ */
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+
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+#define DEBUG 0
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+
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+#if DEBUG
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+ .macro print_character, char
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+ pushw %ax
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+ movb $\char, %al
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+ outb %al, $0xe9
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+ popw %ax
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+ .endm
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+
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+ .macro print_hex_nibble
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+ cmpb $10, %al
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+ sbb $0x69, %al
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+ das
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+ outb %al, $0xe9
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+ .endm
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+
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+ .macro print_hex_byte, reg
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+ pushfl
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+ pushw %ax
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+ movb \reg, %al
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+ pushw %ax
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+ shrb $4, %al
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+ print_hex_nibble
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+ popw %ax
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+ andb $0x0f, %al
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+ print_hex_nibble
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+ popw %ax
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+ popfl
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+ .endm
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+
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+ .macro print_hex_word, reg
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+ pushw %ax
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+ movw \reg, %ax
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+ print_hex_byte %ah
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+ print_hex_byte %al
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+ popw %ax
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+ .endm
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+
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+ .macro print_hex_dword, reg
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+ pushl %eax
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+ movl \reg, %eax
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+ rorl $16, %eax
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+ print_hex_word %ax
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+ rorl $16, %eax
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+ print_hex_word %ax
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+ popl %eax
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+ .endm
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+#else
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+ .macro print_character, char
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+ .endm
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+ .macro print_hex_byte, reg
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+ .endm
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+ .macro print_hex_word, reg
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+ .endm
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+ .macro print_hex_dword, reg
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+ .endm
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+#endif
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+
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+/****************************************************************************
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+ * LZMA parameters and data structures
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+ ****************************************************************************
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+ */
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+
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+/* LZMA decompressor states (as used in XZ Embedded) */
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+#define STATE_LIT_LIT 0x00
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+#define STATE_MATCH_LIT_LIT 0x01
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+#define STATE_REP_LIT_LIT 0x02
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+#define STATE_SHORTREP_LIT_LIT 0x03
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+#define STATE_MATCH_LIT 0x04
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+#define STATE_REP_LIT 0x05
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+#define STATE_SHORTREP_LIT 0x06
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+#define STATE_LIT_MATCH 0x07
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+#define STATE_LIT_LONGREP 0x08
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+#define STATE_LIT_SHORTREP 0x09
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+#define STATE_NONLIT_MATCH 0x0a
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+#define STATE_NONLIT_REP 0x0b
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+
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+/* LZMA maximum decompressor state in which most recent symbol was a literal */
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+#define STATE_LIT_MAX 0x06
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+
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+/* LZMA number of literal context bits ("lc=" parameter) */
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+#define LZMA_LC 2
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+
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+ .struct 0
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+lzma_len_dec:
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+choice: .word 0
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+choice2: .word 0
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+low: .rept ( 1 << 3 )
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+ .word 0
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+ .endr
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+mid: .rept ( 1 << 3 )
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+ .word 0
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+ .endr
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+high: .rept ( 1 << 8 )
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+ .word 0
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+ .endr
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+ .equ sizeof__lzma_len_dec, . - lzma_len_dec
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+ .previous
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+
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+ .struct 0
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+lzma_dec:
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+in_start: .long 0
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+out_start: .long 0
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+rc_code: .long 0
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+rc_range: .long 0
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+len: .word 0
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+reps:
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+rep0: .long 0
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+rep1: .long 0
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+rep2: .long 0
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+rep3: .long 0
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+probs:
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+is_match: .word 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
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+is_rep: .word 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
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+is_rep0: .word 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
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+is_rep1: .word 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
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+is_rep2: .word 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
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+is_rep0_long: .word 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
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+dist_slot: .rept ( 4 * ( 1 << 6 ) )
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+ .word 0
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+ .endr
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+dist_special: .rept ( ( 1 << ( 14 / 2 ) ) - 14 )
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+ .word 0
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+ .endr
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+dist_align: .rept ( 1 << 4 )
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+ .word 0
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+ .endr
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+match_len_dec: .space sizeof__lzma_len_dec
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+rep_len_dec: .space sizeof__lzma_len_dec
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+literal: .rept ( ( 1 << LZMA_LC ) * 0x300 )
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+ .word 0
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+ .endr
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+ .align 4
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+ .equ sizeof__lzma_dec, . - lzma_dec
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+ .previous
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+
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+/*****************************************************************************
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+ * Normalise range encoder
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+ *
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+ * Parameters:
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+ * %ss:%ebp : LZMA parameter block
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+ * %ds:%esi : compressed input data pointer
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+ * Returns:
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+ * %ds:%esi : compressed input data pointer (possibly updated)
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+ * %eax : current range
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+ * Corrupts:
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+ * %eax
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+ *****************************************************************************
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+ */
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+rc_normalise:
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+ /* Check if rc_range is less than 1<<24 */
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+ testb $0xff, (rc_range+3)(%ebp)
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+ jnz 1f
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+ /* If it is, shift in a new byte from the compressed input data */
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+ shll $8, rc_range(%ebp)
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+ shll $8, rc_code(%ebp)
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+ ADDR32 lodsb
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+ movb %al, (rc_code+0)(%ebp)
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+1: /* Return current range */
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+ movl rc_range(%ebp), %eax
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+ ret
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+ .size rc_normalise, . - rc_normalise
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+
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+/*****************************************************************************
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+ * Decode single range-encoded bit using a probability estimate
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+ *
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+ * Parameters:
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+ * %ss:%ebp : LZMA parameter block
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+ * %ds:%esi : compressed input data pointer
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+ * %ebx : probability estimate pointer (offset from %ebp)
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+ * Returns:
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+ * %ds:%esi : compressed input data pointer (possibly updated)
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+ * CF : decoded bit
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+ * ZF : inverse of decoded bit
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+ * Corrupts:
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+ * none
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+ *****************************************************************************
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+ */
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+rc_bit:
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+ /* Preserve registers */
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+ pushl %eax
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+ pushl %edx
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+ /* Perform normalisation */
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+ call rc_normalise
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+ /* Calculate bound in %eax and probability estimate in %dx */
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+ shrl $11, %eax
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+ movzwl (%ebp,%ebx), %edx
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+ mul %edx /* will zero %edx */
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+ movw (%ebp,%ebx), %dx
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+ /* Compare code against bound */
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+ cmpl %eax, rc_code(%ebp)
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+ jae 2f
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+1: /* Code is less than bound */
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+ movl %eax, rc_range(%ebp)
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+ negw %dx
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+ addw $(1<<11), %dx
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+ shrw $5, %dx
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+ addw %dx, (%ebp,%ebx)
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+ xorw %ax, %ax /* Clear CF, set ZF */
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+ jmp 99f
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+2: /* Code is greater than or equal to bound */
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+ subl %eax, rc_range(%ebp)
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+ subl %eax, rc_code(%ebp)
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+ shrw $5, %dx
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+ subw %dx, (%ebp,%ebx)
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+ incw %dx /* Clear ZF (%dx is 11-bit; can never wrap) */
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+ stc /* Set CF */
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+99: /* Restore registers and return */
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+ popl %edx
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+ popl %eax
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+ ret
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+ .size rc_bit, . - rc_bit
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+
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+/*****************************************************************************
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+ * Decode MSB-first bittree
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+ *
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+ * Parameters:
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+ * %ss:%ebp : LZMA parameter block
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+ * %ds:%esi : compressed input data pointer
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+ * %ebx : probability estimate set pointer (offset from %ebp)
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+ * %cx : number of bits to decode
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+ * Returns:
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+ * %ds:%esi : compressed input data pointer (possibly updated)
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+ * %eax : decoded bittree
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+ * Corrupts:
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+ * none
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+ *****************************************************************************
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+ */
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+rc_bittree:
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+ /* Preserve registers */
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+ pushl %edi
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+ pushw %cx
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+ movl %ebx, %edi
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+ /* Initialise registers */
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+ movl $1, %eax
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+1: /* Decode bit */
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+ leaw (%edi,%eax,2), %bx /* high word always zero anyway */
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+ call rc_bit
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+ rclw %ax
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+ ADDR16 loop 1b
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+ /* Restore registers, clear unwanted high bit of result, and return */
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+ movl %edi, %ebx
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+ popw %cx
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+ popl %edi
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+ btrw %cx, %ax
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+ ret
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+ .size rc_bittree, . - rc_bittree
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+
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+/*****************************************************************************
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+ * Decode LSB-first bittree
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+ *
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+ * Parameters:
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+ * %ss:%ebp : LZMA parameter block
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+ * %ds:%esi : compressed input data pointer
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+ * %ebx : probability estimate set pointer (offset from %ebp)
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+ * %cx : number of bits to decode
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+ * Returns:
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+ * %ds:%esi : compressed input data pointer (possibly updated)
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+ * %eax : decoded bittree
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+ * Corrupts:
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+ * none
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+ *****************************************************************************
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+ */
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+rc_bittree_reverse:
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+ /* Preserve registers */
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+ pushw %cx
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+ /* Decode bittree */
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+ call rc_bittree
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+1: /* Reverse result */
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+ rcrb %al
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+ rclb %ah
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+ ADDR16 loop 1b
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+ shrw $8, %ax
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+ /* Restore registers and return */
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+ popw %cx
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+ ret
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+ .size rc_bittree_reverse, . - rc_bittree_reverse
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+
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+/*****************************************************************************
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+ * Decode MSB-first bittree with optional match byte
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+ *
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+ * Parameters:
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+ * %ss:%ebp : LZMA parameter block
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+ * %ds:%esi : compressed input data pointer
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+ * %ebx : probability estimate set pointer (offset from %ebp)
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+ * %cl : match byte
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+ * %ch : 1 to use match byte, 0 to ignore match byte
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+ * Returns:
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+ * %ds:%esi : compressed input data pointer (possibly updated)
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+ * %eax : decoded bittree
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+ * Corrupts:
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+ * none
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+ *****************************************************************************
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+ */
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+rc_bittree_match:
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+ /* Preserve registers */
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+ pushl %edi
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+ pushw %cx
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+ pushw %dx
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+ movl %ebx, %edi
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+ /* Initialise registers */
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+ movl $1, %eax
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+1: /* Decode bit */
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+ rolb $1, %cl
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+ movw %cx, %dx
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|
+ andb %dh, %dl /* match_bit in %dl */
|
|
369
|
+ movw %dx, %bx
|
|
370
|
+ addb %bl, %bh
|
|
371
|
+ xorb %bl, %bl
|
|
372
|
+ addw %ax, %bx /* offset + match_bit + symbol */
|
|
373
|
+ leaw (%edi,%ebx,2), %bx /* high word always zero anyway */
|
|
374
|
+ call rc_bit
|
|
375
|
+ rclw %ax
|
|
376
|
+ movb %al, %dh
|
|
377
|
+ notb %dh
|
|
378
|
+ xorb %dh, %dl
|
|
379
|
+ andb %dl, %ch /* offset &= ( match_bit ^ bit ) */
|
|
380
|
+ testb %ah, %ah
|
|
381
|
+ jz 1b
|
|
382
|
+ /* Restore registers, clear unwanted high bit of result, and return */
|
|
383
|
+ movl %edi, %ebx
|
|
384
|
+ popw %dx
|
|
385
|
+ popw %cx
|
|
386
|
+ popl %edi
|
|
387
|
+ xorb %ah, %ah
|
|
388
|
+ ret
|
|
389
|
+ .size rc_bittree_match, . - rc_bittree_match
|
|
390
|
+
|
|
391
|
+/*****************************************************************************
|
|
392
|
+ * Decode direct bits (no probability estimates)
|
|
393
|
+ *
|
|
394
|
+ * Parameters:
|
|
395
|
+ * %ss:%ebp : LZMA parameter block
|
|
396
|
+ * %ds:%esi : compressed input data pointer
|
|
397
|
+ * %cx : number of bits to decode
|
|
398
|
+ * Returns:
|
|
399
|
+ * %ds:%esi : compressed input data pointer (possibly updated)
|
|
400
|
+ * %eax : decoded bits
|
|
401
|
+ * Corrupts:
|
|
402
|
+ * none
|
|
403
|
+ *****************************************************************************
|
|
404
|
+ */
|
|
405
|
+rc_direct:
|
|
406
|
+ /* Preserve registers */
|
|
407
|
+ pushl %ebx
|
|
408
|
+ pushw %cx
|
|
409
|
+ pushl %edx
|
|
410
|
+ /* Initialise registers */
|
|
411
|
+ xorl %edx, %edx
|
|
412
|
+1: /* Perform normalisation */
|
|
413
|
+ call rc_normalise
|
|
414
|
+ /* Decode bit */
|
|
415
|
+ shrl $1, %eax
|
|
416
|
+ movl %eax, rc_range(%ebp)
|
|
417
|
+ movl rc_code(%ebp), %ebx
|
|
418
|
+ subl %eax, %ebx
|
|
419
|
+ js 2f
|
|
420
|
+ movl %ebx, rc_code(%ebp)
|
|
421
|
+2: rcll %ebx
|
|
422
|
+ rcll %edx
|
|
423
|
+ xorb $1, %dl
|
|
424
|
+ ADDR16 loop 1b
|
|
425
|
+ /* Restore registers and return */
|
|
426
|
+ movl %edx, %eax
|
|
427
|
+ popl %edx
|
|
428
|
+ popw %cx
|
|
429
|
+ popl %ebx
|
|
430
|
+ ret
|
|
431
|
+ .size rc_direct, . - rc_direct
|
|
432
|
+
|
|
433
|
+/*****************************************************************************
|
|
434
|
+ * Decode an LZMA literal
|
|
435
|
+ *
|
|
436
|
+ * Parameters:
|
|
437
|
+ * %ss:%ebp : LZMA parameter block
|
|
438
|
+ * %ds:%esi : compressed input data pointer
|
|
439
|
+ * %es:%edi : uncompressed output data pointer
|
|
440
|
+ * %edx : LZMA state
|
|
441
|
+ * Returns:
|
|
442
|
+ * %ds:%esi : compressed input data pointer (possibly updated)
|
|
443
|
+ * %es:%edi : uncompressed output data pointer (updated)
|
|
444
|
+ * %edx : LZMA state
|
|
445
|
+ * CF : end of payload marker found (always zero)
|
|
446
|
+ * Corrupts:
|
|
447
|
+ * %eax
|
|
448
|
+ * %ebx
|
|
449
|
+ * %ecx
|
|
450
|
+ *****************************************************************************
|
|
451
|
+ *
|
|
452
|
+ * Literals are coded as an eight-bit tree, using a match byte if the
|
|
453
|
+ * previous symbol was not a literal.
|
|
454
|
+ *
|
|
455
|
+ */
|
|
456
|
+lzma_literal:
|
|
457
|
+ /* Get most recent output byte, if available */
|
|
458
|
+ xorl %ebx, %ebx
|
|
459
|
+ cmpl %esi, in_start(%ebp)
|
|
460
|
+ je 1f
|
|
461
|
+ movb %es:-1(%edi), %bh
|
|
462
|
+1: /* Locate probability estimate set */
|
|
463
|
+ shrb $( 8 - LZMA_LC ), %bh
|
|
464
|
+ shlb $1, %bh
|
|
465
|
+ leaw literal(%ebx,%ebx,2), %bx
|
|
466
|
+ /* Get match byte, if applicable */
|
|
467
|
+ xorw %cx, %cx
|
|
468
|
+ cmpb $STATE_LIT_MAX, %dl
|
|
469
|
+ jbe 1f
|
|
470
|
+ movl rep0(%ebp), %eax
|
|
471
|
+ notl %eax
|
|
472
|
+ movb %es:(%edi,%eax), %cl
|
|
473
|
+ movb $1, %ch
|
|
474
|
+1: /* Decode bittree */
|
|
475
|
+ call rc_bittree_match
|
|
476
|
+ /* Store output byte */
|
|
477
|
+ ADDR32 stosb
|
|
478
|
+ print_hex_byte %al
|
|
479
|
+ print_character ' '
|
|
480
|
+ /* Update LZMA state */
|
|
481
|
+ subb $3, %dl
|
|
482
|
+ jns 1f
|
|
483
|
+ xorb %dl, %dl
|
|
484
|
+1: cmpb $7, %dl
|
|
485
|
+ jb 1f
|
|
486
|
+ subb $3, %dl
|
|
487
|
+1: /* Clear CF and return */
|
|
488
|
+ clc
|
|
489
|
+ ret
|
|
490
|
+ .size lzma_literal, . - lzma_literal
|
|
491
|
+
|
|
492
|
+/*****************************************************************************
|
|
493
|
+ * Decode an LZMA length
|
|
494
|
+ *
|
|
495
|
+ * Parameters:
|
|
496
|
+ * %ss:%ebp : LZMA parameter block
|
|
497
|
+ * %ds:%esi : compressed input data pointer
|
|
498
|
+ * %ebx : length parameter pointer (offset from %ebp)
|
|
499
|
+ * Returns:
|
|
500
|
+ * %ds:%esi : compressed input data pointer (possibly updated)
|
|
501
|
+ * Corrupts:
|
|
502
|
+ * %ebx
|
|
503
|
+ *****************************************************************************
|
|
504
|
+ *
|
|
505
|
+ * Lengths are encoded as:
|
|
506
|
+ *
|
|
507
|
+ * "0" + 3 bits : lengths 2-9 ("low")
|
|
508
|
+ * "10" + 3 bits : lengths 10-17 ("mid")
|
|
509
|
+ * "11" + 8 bits : lengths 18-273 ("high")
|
|
510
|
+ */
|
|
511
|
+lzma_len:
|
|
512
|
+ /* Preserve registers */
|
|
513
|
+ pushl %eax
|
|
514
|
+ pushl %ecx
|
|
515
|
+ pushl %edi
|
|
516
|
+ movl %ebx, %edi
|
|
517
|
+ /* Start by assuming three bits and a base length of 2 */
|
|
518
|
+ movw $3, %cx
|
|
519
|
+ movw $2, len(%ebp)
|
|
520
|
+ /* Check low-length choice bit */
|
|
521
|
+ leal choice(%edi), %ebx
|
|
522
|
+ call rc_bit
|
|
523
|
+ leal low(%edi), %ebx
|
|
524
|
+ jz 1f
|
|
525
|
+ /* Check high-length choice bit */
|
|
526
|
+ leal choice2(%edi), %ebx
|
|
527
|
+ call rc_bit
|
|
528
|
+ leal mid(%edi), %ebx
|
|
529
|
+ movb $10, len(%ebp)
|
|
530
|
+ jz 1f
|
|
531
|
+ leal high(%edi), %ebx
|
|
532
|
+ movb $8, %cl
|
|
533
|
+ movb $18, len(%ebp)
|
|
534
|
+1: /* Get encoded length */
|
|
535
|
+ call rc_bittree
|
|
536
|
+ addw %ax, len(%ebp)
|
|
537
|
+ /* Restore registers and return */
|
|
538
|
+ movl %edi, %ebx
|
|
539
|
+ popl %edi
|
|
540
|
+ popl %ecx
|
|
541
|
+ popl %eax
|
|
542
|
+ ret
|
|
543
|
+ .size lzma_len, . - lzma_len
|
|
544
|
+
|
|
545
|
+/*****************************************************************************
|
|
546
|
+ * Copy (possibly repeated) matched data
|
|
547
|
+ *
|
|
548
|
+ * Parameters:
|
|
549
|
+ * %ss:%ebp : LZMA parameter block
|
|
550
|
+ * %ds:%esi : compressed input data pointer
|
|
551
|
+ * %es:%edi : uncompressed output data pointer
|
|
552
|
+ * %cl : repeated match distance index (for repeated matches)
|
|
553
|
+ * %eax : match distance (for non-repeated matches)
|
|
554
|
+ * Returns:
|
|
555
|
+ * %ds:%esi : compressed input data pointer (possibly updated)
|
|
556
|
+ * %es:%edi : uncompressed output data pointer
|
|
557
|
+ * CF : match distance is out of range
|
|
558
|
+ * Corrupts:
|
|
559
|
+ * %eax
|
|
560
|
+ * %ebx
|
|
561
|
+ * %ecx
|
|
562
|
+ *****************************************************************************
|
|
563
|
+ */
|
|
564
|
+match: /* Update repeated match list */
|
|
565
|
+ print_character '['
|
|
566
|
+ movl $3, %ecx
|
|
567
|
+ jmp 1f
|
|
568
|
+match_rep:
|
|
569
|
+ print_character '['
|
|
570
|
+ print_character 'R'
|
|
571
|
+ print_hex_byte %cl
|
|
572
|
+ print_character '='
|
|
573
|
+ movzbl %cl, %ecx
|
|
574
|
+ movl reps(%ebp,%ecx,4), %eax
|
|
575
|
+ jcxz 2f
|
|
576
|
+1: movl (reps-4)(%ebp,%ecx,4), %ebx
|
|
577
|
+ movl %ebx, reps(%ebp,%ecx,4)
|
|
578
|
+ loop 1b
|
|
579
|
+ movl %eax, rep0(%ebp)
|
|
580
|
+2: /* Preserve registers */
|
|
581
|
+ pushl %esi
|
|
582
|
+ /* Get stored match length */
|
|
583
|
+ movzwl len(%ebp), %ecx
|
|
584
|
+ print_hex_dword %eax
|
|
585
|
+ print_character '+'
|
|
586
|
+ print_hex_word %cx
|
|
587
|
+ print_character ']'
|
|
588
|
+ print_character ' '
|
|
589
|
+ /* Abort with CF set if match distance is out of range */
|
|
590
|
+ movl out_start(%ebp), %esi
|
|
591
|
+ negl %esi
|
|
592
|
+ leal -1(%edi,%esi), %esi
|
|
593
|
+ cmpl %eax, %esi
|
|
594
|
+ jc 99f
|
|
595
|
+ /* Perform copy */
|
|
596
|
+ notl %eax
|
|
597
|
+ leal (%edi,%eax), %esi
|
|
598
|
+ ADDR32 es rep movsb
|
|
599
|
+99: /* Restore registers and return */
|
|
600
|
+ popl %esi
|
|
601
|
+ ret
|
|
602
|
+ .size match, . - match
|
|
603
|
+
|
|
604
|
+/*****************************************************************************
|
|
605
|
+ * Decode an LZMA match
|
|
606
|
+ *
|
|
607
|
+ * Parameters:
|
|
608
|
+ * %ss:%ebp : LZMA parameter block
|
|
609
|
+ * %ds:%esi : compressed input data pointer
|
|
610
|
+ * %es:%edi : uncompressed output data pointer
|
|
611
|
+ * %edx : LZMA state
|
|
612
|
+ * Returns:
|
|
613
|
+ * %ds:%esi : compressed input data pointer (possibly updated)
|
|
614
|
+ * %es:%edi : uncompressed output data pointer
|
|
615
|
+ * %edx : LZMA state
|
|
616
|
+ * CF : end of payload marker found
|
|
617
|
+ * Corrupts:
|
|
618
|
+ * %eax
|
|
619
|
+ * %ebx
|
|
620
|
+ * %ecx
|
|
621
|
+ *****************************************************************************
|
|
622
|
+ *
|
|
623
|
+ * Matches are encoded as an LZMA length followed by a 6-bit "distance
|
|
624
|
+ * slot" code, 0-26 fixed-probability bits, and 0-5 context encoded
|
|
625
|
+ * bits.
|
|
626
|
+ */
|
|
627
|
+lzma_match:
|
|
628
|
+ /* Preserve registers */
|
|
629
|
+ pushl %edi
|
|
630
|
+ /* Update LZMA state */
|
|
631
|
+ cmpb $STATE_LIT_MAX, %dl
|
|
632
|
+ movb $STATE_LIT_MATCH, %dl
|
|
633
|
+ jbe 1f
|
|
634
|
+ movb $STATE_NONLIT_MATCH, %dl
|
|
635
|
+1: /* Decode length */
|
|
636
|
+ movl $match_len_dec, %ebx
|
|
637
|
+ call lzma_len
|
|
638
|
+ /* Decode distance slot */
|
|
639
|
+ movw len(%ebp), %bx
|
|
640
|
+ subw $2, %bx
|
|
641
|
+ cmpw $4, %bx
|
|
642
|
+ jb 1f
|
|
643
|
+ movw $3, %bx
|
|
644
|
+1: shlw $7, %bx
|
|
645
|
+ addw $dist_slot, %bx
|
|
646
|
+ movw $6, %cx
|
|
647
|
+ call rc_bittree
|
|
648
|
+ /* Distance slots 0-3 are literal distances */
|
|
649
|
+ cmpb $4, %al
|
|
650
|
+ jb 99f
|
|
651
|
+ /* Determine initial bits: 10/11 for even/odd distance codes */
|
|
652
|
+ movl %eax, %edi
|
|
653
|
+ andw $1, %di
|
|
654
|
+ orw $2, %di
|
|
655
|
+ /* Determine number of context-encoded bits */
|
|
656
|
+ movw %ax, %cx
|
|
657
|
+ shrb $1, %cl
|
|
658
|
+ decb %cl
|
|
659
|
+ /* Select context to be used in absence of fixed-probability bits */
|
|
660
|
+ movl %edi, %ebx
|
|
661
|
+ shlw %cl, %bx
|
|
662
|
+ subw %ax, %bx
|
|
663
|
+ leaw (dist_special-2)(%ebx,%ebx), %bx
|
|
664
|
+ /* Decode fixed-probability bits, if any */
|
|
665
|
+ cmpb $6, %cl
|
|
666
|
+ jb 1f
|
|
667
|
+ subb $4, %cl
|
|
668
|
+ shll %cl, %edi
|
|
669
|
+ call rc_direct
|
|
670
|
+ orl %eax, %edi
|
|
671
|
+ /* Select context to be used in presence of fixed-probability bits */
|
|
672
|
+ movb $4, %cl
|
|
673
|
+ movl $dist_align, %ebx
|
|
674
|
+1: /* Decode context-encoded bits */
|
|
675
|
+ shll %cl, %edi
|
|
676
|
+ call rc_bittree_reverse
|
|
677
|
+ orl %edi, %eax
|
|
678
|
+99: /* Restore registers and tail-call */
|
|
679
|
+ popl %edi
|
|
680
|
+ jmp match
|
|
681
|
+ .size lzma_match, . - lzma_match
|
|
682
|
+
|
|
683
|
+/*****************************************************************************
|
|
684
|
+ * Decode an LZMA repeated match
|
|
685
|
+ *
|
|
686
|
+ * Parameters:
|
|
687
|
+ * %ss:%ebp : LZMA parameter block
|
|
688
|
+ * %ds:%esi : compressed input data pointer
|
|
689
|
+ * %es:%edi : uncompressed output data pointer
|
|
690
|
+ * %edx : LZMA state
|
|
691
|
+ * Returns:
|
|
692
|
+ * %ds:%esi : compressed input data pointer (possibly updated)
|
|
693
|
+ * %es:%edi : uncompressed output data pointer
|
|
694
|
+ * %edx : LZMA state
|
|
695
|
+ * CF : end of payload marker found
|
|
696
|
+ * Corrupts:
|
|
697
|
+ * %eax
|
|
698
|
+ * %ebx
|
|
699
|
+ * %ecx
|
|
700
|
+ *****************************************************************************
|
|
701
|
+ *
|
|
702
|
+ * Repeated matches are encoded as:
|
|
703
|
+ *
|
|
704
|
+ * "00" : shortrep0 (implicit length 1)
|
|
705
|
+ * "01" + len : longrep0
|
|
706
|
+ * "10" + len : longrep1
|
|
707
|
+ * "110" + len : longrep2
|
|
708
|
+ * "111" + len : longrep3
|
|
709
|
+ */
|
|
710
|
+lzma_rep_match:
|
|
711
|
+ /* Initially assume longrep0 */
|
|
712
|
+ movw $(STATE_LIT_LONGREP << 8), %cx
|
|
713
|
+ /* Get is_rep0 bit */
|
|
714
|
+ leal is_rep0(,%edx,2), %ebx
|
|
715
|
+ call rc_bit
|
|
716
|
+ jnz 1f
|
|
717
|
+ /* Get is_rep0_long bit */
|
|
718
|
+ leal is_rep0_long(,%edx,2), %ebx
|
|
719
|
+ call rc_bit
|
|
720
|
+ jnz 98f
|
|
721
|
+ movw $1, len(%ebp)
|
|
722
|
+ movb $STATE_LIT_SHORTREP, %ch
|
|
723
|
+ jmp 99f
|
|
724
|
+1: /* Get is_rep1 bit */
|
|
725
|
+ incb %cl
|
|
726
|
+ leal is_rep1(,%edx,2), %ebx
|
|
727
|
+ call rc_bit
|
|
728
|
+ jz 98f
|
|
729
|
+ /* Get is_rep2 bit */
|
|
730
|
+ incb %cl
|
|
731
|
+ leal is_rep2(,%edx,2), %ebx
|
|
732
|
+ call rc_bit
|
|
733
|
+ adcb $0, %cl
|
|
734
|
+98: /* Decode length */
|
|
735
|
+ movl $rep_len_dec, %ebx
|
|
736
|
+ call lzma_len
|
|
737
|
+99: /* Update LZMA state */
|
|
738
|
+ cmpb $STATE_LIT_MAX, %dl
|
|
739
|
+ movb %ch, %dl
|
|
740
|
+ jbe 1f
|
|
741
|
+ movb $STATE_NONLIT_REP, %dl
|
|
742
|
+1: /* Tail call */
|
|
743
|
+ jmp match_rep
|
|
744
|
+ .size lzma_match, . - lzma_match
|
|
745
|
+
|
|
746
|
+/*****************************************************************************
|
|
747
|
+ * Decode one LZMA symbol
|
|
748
|
+ *
|
|
749
|
+ * Parameters:
|
|
750
|
+ * %ss:%ebp : LZMA parameter block
|
|
751
|
+ * %ds:%esi : compressed input data pointer
|
|
752
|
+ * %es:%edi : uncompressed output data pointer
|
|
753
|
+ * %edx : LZMA state
|
|
754
|
+ * Returns:
|
|
755
|
+ * %ds:%esi : compressed input data pointer (possibly updated)
|
|
756
|
+ * %es:%edi : uncompressed output data pointer (updated)
|
|
757
|
+ * %edx : LZMA state
|
|
758
|
+ * CF : end of payload marker found
|
|
759
|
+ * Corrupts:
|
|
760
|
+ * %eax
|
|
761
|
+ * %ebx
|
|
762
|
+ * %ecx
|
|
763
|
+ *****************************************************************************
|
|
764
|
+ */
|
|
765
|
+lzma_decode:
|
|
766
|
+ /* Get is_match bit */
|
|
767
|
+ leal is_match(,%edx,2), %ebx
|
|
768
|
+ call rc_bit
|
|
769
|
+ jz lzma_literal
|
|
770
|
+ /* Get is_rep bit */
|
|
771
|
+ leal is_rep(,%edx,2), %ebx
|
|
772
|
+ call rc_bit
|
|
773
|
+ jz lzma_match
|
|
774
|
+ jmp lzma_rep_match
|
|
775
|
+ .size lzma_decode, . - lzma_decode
|
|
776
|
+
|
|
777
|
+/****************************************************************************
|
|
778
|
+ * Undo effect of branch-call-jump (BCJ) filter
|
|
779
|
+ *
|
|
780
|
+ * Parameters:
|
|
781
|
+ * %es:%esi : start of uncompressed output data (note %es)
|
|
782
|
+ * %es:%edi : end of uncompressed output data
|
|
783
|
+ * Returns:
|
|
784
|
+ * Corrupts:
|
|
785
|
+ * %eax
|
|
786
|
+ * %ebx
|
|
787
|
+ * %ecx
|
|
788
|
+ * %edx
|
|
789
|
+ * %esi
|
|
790
|
+ *****************************************************************************
|
|
791
|
+ */
|
|
792
|
+bcj_filter:
|
|
793
|
+ /* Store (negative) start of data in %edx */
|
|
794
|
+ movl %esi, %edx
|
|
795
|
+ negl %edx
|
|
796
|
+ /* Calculate limit in %ecx */
|
|
797
|
+ leal -5(%edi,%edx), %ecx
|
|
798
|
+1: /* Calculate offset in %ebx */
|
|
799
|
+ leal (%esi,%edx), %ebx
|
|
800
|
+ /* Check for end of data */
|
|
801
|
+ cmpl %ecx, %ebx
|
|
802
|
+ ja 99f
|
|
803
|
+ /* Check for an opcode which would be followed by a rel32 address */
|
|
804
|
+ ADDR32 es lodsb
|
|
805
|
+ andb $0xfe, %al
|
|
806
|
+ cmpb $0xe8, %al
|
|
807
|
+ jne 1b
|
|
808
|
+ /* Get current jump target value in %eax */
|
|
809
|
+ ADDR32 es lodsl
|
|
810
|
+ /* Convert absolute addresses in the range [0,limit) back to
|
|
811
|
+ * relative addresses in the range [-offset,limit-offset).
|
|
812
|
+ */
|
|
813
|
+ cmpl %ecx, %eax
|
|
814
|
+ jae 2f
|
|
815
|
+ subl %ebx,%es:-4(%esi)
|
|
816
|
+2: /* Convert negative numbers in the range [-offset,0) back to
|
|
817
|
+ * positive numbers in the range [limit-offset,limit).
|
|
818
|
+ */
|
|
819
|
+ notl %eax /* Range is now [0,offset) */
|
|
820
|
+ cmpl %ebx, %eax
|
|
821
|
+ jae 1b
|
|
822
|
+ addl %ecx,%es:-4(%esi)
|
|
823
|
+ jmp 1b
|
|
824
|
+99: /* Return */
|
|
825
|
+ ret
|
|
826
|
+ .size bcj_filter, . - bcj_filter
|
|
827
|
+
|
|
828
|
+/****************************************************************************
|
|
829
|
+ * decompress (real-mode or 16/32-bit protected-mode near call)
|
|
830
|
+ *
|
|
831
|
+ * Decompress data
|
|
832
|
+ *
|
|
833
|
+ * Parameters (passed via registers):
|
|
834
|
+ * %ds:%esi : Start of compressed input data
|
|
835
|
+ * %es:%edi : Start of output buffer
|
|
836
|
+ * Returns:
|
|
837
|
+ * %ds:%esi - End of compressed input data
|
|
838
|
+ * %es:%edi - End of decompressed output data
|
|
839
|
+ * All other registers are preserved
|
|
840
|
+ *
|
|
841
|
+ * NOTE: It would be possible to build a smaller version of the
|
|
842
|
+ * decompression code for -DKEEP_IT_REAL by using 16-bit registers
|
|
843
|
+ * where possible.
|
|
844
|
+ ****************************************************************************
|
|
845
|
+ */
|
|
846
|
+ .globl decompress
|
|
847
|
+decompress:
|
|
848
|
+ /* Preserve registers */
|
|
849
|
+ pushl %eax
|
|
850
|
+ pushl %ebx
|
|
851
|
+ pushl %ecx
|
|
852
|
+ pushl %edx
|
|
853
|
+ pushl %ebp
|
|
854
|
+ /* Allocate parameter block */
|
|
855
|
+ subl $sizeof__lzma_dec, %esp
|
|
856
|
+ movl %esp, %ebp
|
|
857
|
+ /* Zero parameter block and set all probabilities to 0.5 */
|
|
858
|
+ pushl %edi
|
|
859
|
+ pushw %es
|
|
860
|
+ pushw %ss
|
|
861
|
+ popw %es
|
|
862
|
+ movl %ebp, %edi
|
|
863
|
+ xorl %eax, %eax
|
|
864
|
+ movl $( sizeof__lzma_dec / 4 ), %ecx
|
|
865
|
+ ADDR32 rep stosl
|
|
866
|
+ leal probs(%ebp), %edi
|
|
867
|
+ movw $( ( 1 << 11 ) / 2 ), %ax
|
|
868
|
+ movl $( ( sizeof__lzma_dec - probs ) / 2 ), %ecx
|
|
869
|
+ ADDR32 rep stosw
|
|
870
|
+ popw %es
|
|
871
|
+ popl %edi
|
|
872
|
+ /* Initialise remaining parameters */
|
|
873
|
+ movl %esi, in_start(%ebp)
|
|
874
|
+ movl %edi, out_start(%ebp)
|
|
875
|
+ print_character '\n'
|
|
876
|
+ ADDR32 lodsb /* discard initial byte */
|
|
877
|
+ print_hex_byte %al
|
|
878
|
+ ADDR32 lodsl
|
|
879
|
+ bswapl %eax
|
|
880
|
+ print_hex_dword %eax
|
|
881
|
+ print_character '\n'
|
|
882
|
+ movl %eax, rc_code(%ebp)
|
|
883
|
+ decl rc_range(%ebp)
|
|
884
|
+ movl $STATE_LIT_LIT, %edx
|
|
885
|
+1: /* Decompress until we reach end of buffer */
|
|
886
|
+ call lzma_decode
|
|
887
|
+ jnc 1b
|
|
888
|
+ print_character '\n'
|
|
889
|
+ /* Undo BCJ filter */
|
|
890
|
+ pushl %esi
|
|
891
|
+ movl out_start(%ebp), %esi
|
|
892
|
+ call bcj_filter
|
|
893
|
+ popl %esi
|
|
894
|
+ /* Restore registers and return */
|
|
895
|
+ addl $sizeof__lzma_dec, %esp
|
|
896
|
+ popl %ebp
|
|
897
|
+ popl %edx
|
|
898
|
+ popl %ecx
|
|
899
|
+ popl %ebx
|
|
900
|
+ popl %eax
|
|
901
|
+ ret
|
|
902
|
+
|
|
903
|
+ /* Specify minimum amount of stack space required */
|
|
904
|
+ .globl _min_decompress_stack
|
|
905
|
+ .equ _min_decompress_stack, ( sizeof__lzma_dec + 512 /* margin */ )
|