[fbcon] Allow character height to be selected at runtime

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/arch/i386/interface/pcbios/vesafb.c

 #define CONSOLE_VESAFB ( CONSOLE_USAGE_ALL & ~CONSOLE_USAGE_LOG )
 #endif
 
+/** Character height */
+#define VESAFB_CHAR_HEIGHT 16
+
 /** Font corresponding to selected character width and height */
 #define VESAFB_FONT VBE_FONT_8x16
 
 	struct fbcon_colour_map map;
 	/** Font definition */
 	struct fbcon_font font;
+	/** Character glyphs */
+	struct segoff glyphs;
 	/** Saved VGA mode */
 	uint8_t saved_mode;
 };
 	return ( code ? -EIO_VBE ( code ) : 0 );
 }
 
+/**
+ * Get character glyph
+ *
+ * @v character		Character
+ * @v glyph		Character glyph to fill in
+ */
+static void vesafb_glyph ( unsigned int character, uint8_t *glyph ) {
+	size_t offset = ( character * VESAFB_CHAR_HEIGHT );
+
+	copy_from_real ( glyph, vesafb.glyphs.segment,
+			 ( vesafb.glyphs.offset + offset ), VESAFB_CHAR_HEIGHT);
+}
+
 /**
  * Get font definition
  *
  */
 static void vesafb_font ( void ) {
-	struct segoff font;
 
 	/* Get font information
 	 *
 					   "movw %%es, %%cx\n\t"
 					   "movw %%bp, %%dx\n\t"
 					   "popw %%bp\n\t" /* gcc bug */ )
-			       : "=c" ( font.segment ),
-				 "=d" ( font.offset )
+			       : "=c" ( vesafb.glyphs.segment ),
+				 "=d" ( vesafb.glyphs.offset )
 			       : "a" ( VBE_GET_FONT ),
 				 "b" ( VESAFB_FONT ) );
 	DBGC ( &vbe_buf, "VESAFB has font %04x at %04x:%04x\n",
-	       VESAFB_FONT, font.segment, font.offset );
-	vesafb.font.start = real_to_user ( font.segment, font.offset );
+	       VESAFB_FONT, vesafb.glyphs.segment, vesafb.glyphs.offset );
+	vesafb.font.height = VESAFB_CHAR_HEIGHT;
+	vesafb.font.glyph = vesafb_glyph;
 }
 
 /**

src/core/fbcon.c

  */
 static void fbcon_draw ( struct fbcon *fbcon, struct fbcon_text_cell *cell,
 			 unsigned int xpos, unsigned int ypos ) {
-	struct fbcon_font_glyph glyph;
+	uint8_t glyph[fbcon->font->height];
 	size_t offset;
 	size_t pixel_len;
 	size_t skip_len;
 	void *src;
 
 	/* Get font character */
-	copy_from_user ( &glyph, fbcon->font->start,
-			 ( cell->character * sizeof ( glyph ) ),
-			 sizeof ( glyph ) );
+	fbcon->font->glyph ( cell->character, glyph );
 
 	/* Calculate pixel geometry */
 	offset = ( fbcon->indent +
 	transparent = ( cell->background == FBCON_TRANSPARENT );
 
 	/* Draw character rows */
-	for ( row = 0 ; row < FBCON_CHAR_HEIGHT ; row++ ) {
+	for ( row = 0 ; row < fbcon->font->height ; row++ ) {
 
 		/* Draw background picture, if applicable */
 		if ( transparent ) {
 		}
 
 		/* Draw character row */
-		for ( column = FBCON_CHAR_WIDTH, bitmask = glyph.bitmask[row] ;
+		for ( column = FBCON_CHAR_WIDTH, bitmask = glyph[row] ;
 		      column ; column--, bitmask <<= 1, offset += pixel_len ) {
 			if ( bitmask & 0x80 ) {
 				src = &cell->foreground;
 	/* Expand margin to accommodate whole characters */
 	width = ( pixel->width - margin->left - margin->right );
 	height = ( pixel->height - margin->top - margin->bottom );
-	if ( ( width < FBCON_CHAR_WIDTH ) || ( height < FBCON_CHAR_HEIGHT ) ) {
+	if ( ( width < FBCON_CHAR_WIDTH ) ||
+	     ( height < ( ( int ) font->height ) ) ) {
 		DBGC ( fbcon, "FBCON %p has unusable character area "
 		       "[%d-%d),[%d-%d)\n", fbcon,
 		       margin->left, ( pixel->width - margin->right ),
 		goto err_margin;
 	}
 	xgap = ( width % FBCON_CHAR_WIDTH );
-	ygap = ( height % FBCON_CHAR_HEIGHT );
+	ygap = ( height % font->height );
 	fbcon->margin.left = ( margin->left + ( xgap / 2 ) );
 	fbcon->margin.top = ( margin->top + ( ygap / 2 ) );
 	fbcon->margin.right = ( margin->right + ( xgap - ( xgap / 2 ) ) );
 
 	/* Derive character geometry from pixel geometry */
 	fbcon->character.width = ( width / FBCON_CHAR_WIDTH );
-	fbcon->character.height = ( height / FBCON_CHAR_HEIGHT );
+	fbcon->character.height = ( height / font->height );
 	fbcon->character.len = ( pixel->len * FBCON_CHAR_WIDTH );
-	fbcon->character.stride = ( pixel->stride * FBCON_CHAR_HEIGHT );
+	fbcon->character.stride = ( pixel->stride * font->height );
 	DBGC ( fbcon, "FBCON %p is pixel %dx%d, char %dx%d at "
 	       "[%d-%d),[%d-%d)\n", fbcon, fbcon->pixel->width,
 	       fbcon->pixel->height, fbcon->character.width,

src/include/ipxe/fbcon.h

 /** Character width, in pixels */
 #define FBCON_CHAR_WIDTH 9
 
-/** Character height, in pixels */
-#define FBCON_CHAR_HEIGHT 16
-
 /** Bold colour modifier (RGB value) */
 #define FBCON_BOLD 0x555555
 
 /** A font glyph */
 struct fbcon_font_glyph {
 	/** Row bitmask */
-	uint8_t bitmask[FBCON_CHAR_HEIGHT];
-} __attribute__ (( packed ));
+	uint8_t bitmask[0];
+};
 
 /** A font definition */
 struct fbcon_font {
-	/** Character glyphs */
-	userptr_t start;
-} __attribute__ (( packed ));
+	/** Character height (in pixels) */
+	unsigned int height;
+	/**
+	 * Get character glyph
+	 *
+	 * @v character		Character
+	 * @v glyph		Character glyph to fill in
+	 */
+	void ( * glyph ) ( unsigned int character, uint8_t *glyph );
+};
 
 /** A frame buffer geometry
  *