Changeset 443 in xtideuniversalbios for trunk/XTIDE_Universal_BIOS/Src/Device/IDE/IdeIO.asm

Timestamp:

Aug 25, 2012, 2:48:40 PM (12 years ago)

Author:

aitotat@…

google:author:

aitotat@gmail.com

Message:

Changes to XTIDE Universal BIOS:

• Offset to ATA-ID buffer will no longer get corrupted when trying to enable 8-bit mode for XT-CF.
• Optimized A0<->A3 swapping a bit.

File:

• trunk/XTIDE_Universal_BIOS/Src/Device/IDE/IdeIO.asm (modified) (1 diff)

trunk/XTIDE_Universal_BIOS/Src/Device/IDE/IdeIO.asm

@@ -163 +163 @@
     ; Exchange address lines A0 and A3 from DL
     add     dx, [cs:bx]                         ; DX now has port address
-    mov     bl, dl
-    mov     bh, MASK_A3_AND_A0_ADDRESS_LINES
-    and     bh, bl                              ; BH = 0, 1, 8 or 9, we can ignore 0 and 9
-    jz      SHORT .ReturnTranslatedPortInDX     ; Jump out since DH is 0
-    xor     bh, MASK_A3_AND_A0_ADDRESS_LINES
-    jz      SHORT .ReturnTranslatedPortInDX     ; Jump out since DH was 9
-    and     dl, ~MASK_A3_AND_A0_ADDRESS_LINES
-    or      dl, bh                              ; Address lines now reversed
+    mov     bl, dl                              ; Port low byte to BL
+    and     bl, MASK_A3_AND_A0_ADDRESS_LINES    ; Clear all bits except A0 and A3
+    jz      SHORT .ReturnTranslatedPortInDX     ; A0 and A3 both zeroes, no change needed
+    cmp     bl, MASK_A3_AND_A0_ADDRESS_LINES
+    je      SHORT .ReturnTranslatedPortInDX     ; A0 and A3 both ones, no change needed
+    xor     dl, MASK_A3_AND_A0_ADDRESS_LINES    ; Invert A0 and A3
 .ReturnTranslatedPortInDX:
     ret