You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.

bitbash.c 1.8KB

1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162
  1. /*
  2. * Copyright (C) 2006 Michael Brown <mbrown@fensystems.co.uk>.
  3. *
  4. * This program is free software; you can redistribute it and/or
  5. * modify it under the terms of the GNU General Public License as
  6. * published by the Free Software Foundation; either version 2 of the
  7. * License, or any later version.
  8. *
  9. * This program is distributed in the hope that it will be useful, but
  10. * WITHOUT ANY WARRANTY; without even the implied warranty of
  11. * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  12. * General Public License for more details.
  13. *
  14. * You should have received a copy of the GNU General Public License
  15. * along with this program; if not, write to the Free Software
  16. * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  17. * 02110-1301, USA.
  18. *
  19. * You can also choose to distribute this program under the terms of
  20. * the Unmodified Binary Distribution Licence (as given in the file
  21. * COPYING.UBDL), provided that you have satisfied its requirements.
  22. */
  23. FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
  24. #include <ipxe/bitbash.h>
  25. /** @file
  26. *
  27. * Bit-bashing interfaces
  28. *
  29. */
  30. /**
  31. * Set/clear output bit
  32. *
  33. * @v basher Bit-bashing interface
  34. * @v bit_id Bit number
  35. * @v data Value to write
  36. *
  37. * If @c data is 0, a logic 0 will be written. If @c data is
  38. * non-zero, a logic 1 will be written.
  39. */
  40. void write_bit ( struct bit_basher *basher, unsigned int bit_id,
  41. unsigned long data ) {
  42. basher->op->write ( basher, bit_id, ( data ? -1UL : 0 ) );
  43. }
  44. /**
  45. * Read input bit
  46. *
  47. * @v basher Bit-bashing interface
  48. * @v bit_id Bit number
  49. * @ret data Value read
  50. *
  51. * @c data will always be either 0 or -1UL. The idea is that the
  52. * caller can simply binary-AND the returned value with whatever mask
  53. * it needs to apply.
  54. */
  55. int read_bit ( struct bit_basher *basher, unsigned int bit_id ) {
  56. return ( basher->op->read ( basher, bit_id ) ? -1UL : 0 );
  57. }