1. lcd_grey_data:
  2. lea.l (-2*4, %sp), %sp
  3. movem.l %a2-%a3, (%sp)
  4. movem.l (2*4+4, %sp), %a0-%a2 /* values, phases, length */
  5. lea.l LCD_BASE_ADDRESS+2, %a3 /* LCD data port address */
  6. .ph_loop:
  7. clr.l %d1
  8. move.l (%a1), %d0 /* fetch 4 pixel phases */
  9. bclr.l #31, %d0 /* Z = !(p0 & 0x80); p0 &= ~0x80; */
  10. seq.b %d1 /* %d1 = ........................00000000 */
  11. lsl.l #1, %d1 /* %d1 = .......................00000000. */
  12. bclr.l #23, %d0 /* Z = !(p1 & 0x80); p1 &= ~0x80; */
  13. seq.b %d1 /* %d1 = .......................011111111 */
  14. lsl.l #1, %d1 /* %d1 = ......................011111111. */
  15. bclr.l #15, %d0 /* Z = !(p2 & 0x80); p2 &= ~0x80; */
  16. seq.b %d1 /* %d1 = ......................0122222222 */
  17. lsl.l #1, %d1 /* %d1 = .....................0122222222. */
  18. bclr.l #7, %d0 /* Z = !(p3 & 0x80); p3 &= ~0x80; */
  19. seq.b %d1 /* %d1 = .....................01233333333 */
  20. lsr.l #7, %d1 /* %d1 = ............................0123 */
  21. add.l (%a0)+, %d0 /* add 4 pixel values to the phases */
  22. move.l %d0, (%a1)+ /* store new phases, advance pointer */
  23.  
  24. move.w %d1, (%a3) /* transfer to lcd */
  25.  
  26. cmp.l %a2, %a1
  27. bls .ph_loop
  28.  
  29. movem.l (%sp), %a2-%a3
  30. lea.l (2*4, %sp), %sp
  31. rts