Changeset 476 in xtideuniversalbios for trunk/XTIDE_Universal_BIOS

Timestamp:

Oct 13, 2012, 4:14:58 PM (12 years ago)

Author:

aitotat@…

google:author:

aitotat@gmail.com

Message:

Changes to XTIDE Universal BIOS:

• Memory Mapped Transfers now work again.

File:

• trunk/XTIDE_Universal_BIOS/Src/Device/IDE/JrIdeTransfer.asm (modified) (2 diffs)

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

@@ -117 +117 @@
     jc      SHORT ReturnWithMemoryIOtransferErrorInAH
 
-    ; Increment number of successfully read sectors
+    ; Update number of successfully read sectors and sectors left to transfer.
+    ; We cannot use SUB instruction as a comparison since it will not
+    ; work in this situation:
+    ; Before SUB we have 2 full blocks left to transfer. SUB command
+    ; then compares 2 full blocks against one full block and updates
+    ; sectors left to one full block and jumps to .ReadNextBlockFromDrive,
+    ; since we have one full block left to transfer. After it has been
+    ; transferred, there will be a wait for next block but DRQ is never
+    ; set since all is transferred! Then we get timeout error.
     mov     cx, [bp+MEMPIOVARS.wSectorsInBlock]
+    sub     [bp+MEMPIOVARS.bSectorsLeft], cl
     add     [bp+MEMPIOVARS.bSectorsDone], cl
-    sub     [bp+MEMPIOVARS.bSectorsLeft], cl
+    cmp     [bp+MEMPIOVARS.bSectorsLeft], cl
     ja      SHORT .ReadNextBlockFromDrive
 
@@ -191 +200 @@
     ; Increment number of successfully written WORDs
     mov     cx, [bp+MEMPIOVARS.wSectorsInBlock]
+    sub     [bp+MEMPIOVARS.bSectorsLeft], cl
     add     [bp+MEMPIOVARS.bSectorsDone], cl
-    sub     [bp+MEMPIOVARS.bSectorsLeft], cl
+    cmp     [bp+MEMPIOVARS.bSectorsLeft], cl
     ja      SHORT .WriteNextBlockToDrive