Changeset 241 in xtideuniversalbios for trunk/XTIDE_Universal_BIOS/Src/Boot/BootInfo.asm

Timestamp:

Feb 9, 2012, 11:08:59 AM (12 years ago)

Author:

gregli@…

google:author:

gregli@hotmail.com

Message:

Space optimizations in the Boot Menu and BootInfo routines, taking advantage of nested %s. Optimization in the init of RamVars to avoid writing the signature twice. Preparing for addition of serial floppy support, starting to break the assumption that our drives are always 80h or higher.

File:

• trunk/XTIDE_Universal_BIOS/Src/Boot/BootInfo.asm (modified) (6 diffs)

trunk/XTIDE_Universal_BIOS/Src/Boot/BootInfo.asm

@@ -16 +16 @@
 ;   Returns:
 ;       ES:BX:  Ptr to BOOTNFO (if successful)
-;       CF:     Cleared if BOOTNFO created succesfully
-;               Set if any error
 ;   Corrupts registers:
-;       AX, BX, CX, DX
+;       AX, BX, CX, DX, DI, SI
 ;--------------------------------------------------------------------
 BootInfo_CreateForHardDisk:
-    call    BootInfo_GetOffsetToBX      ; ES:BX now points to new BOOTNFO
-    ; Fall to .StoreSectorCount
+    call    BootInfo_ConvertDPTtoBX     ; ES:BX now points to new BOOTNFO
+    push    bx                          ; Preserve for return
 
-;--------------------------------------------------------------------
-; .StoreSectorCount
-;   Parameters:
-;       ES:BX:  Ptr to BOOTNFO
-;       ES:SI:  Ptr to 512-byte ATA information read from the drive
-;       DS:DI:  Ptr to Disk Parameter Table
-;   Returns:
-;       Nothing
-;   Corrupts registers:
-;       AX, CX, DX
-;--------------------------------------------------------------------
-.StoreSectorCount:
-    push    bx
-    call    AtaID_GetTotalSectorCountToBXDXAXfromAtaInfoInESSI
-    mov     cx, bx                          ; Now in CX:DX:AX
-    pop     bx
-    mov     [es:bx+BOOTNFO.twSectCnt], ax
-    mov     [es:bx+BOOTNFO.twSectCnt+2], dx
-    mov     [es:bx+BOOTNFO.twSectCnt+4], cx
-    ; Fall to .StoreDriveName
+    mov     di, bx                      ; Starting pointer at beginning of structure
 
-;--------------------------------------------------------------------
-; .StoreDriveName
-;   Parameters:
-;       ES:BX:  Ptr to BOOTNFO
-;       ES:SI:  Ptr to 512-byte ATA information read from the drive
-;       DS:DI:  Ptr to Disk Parameter Table
-;   Returns:
-;       CF:     Cleared if variables stored succesfully
-;               Set if any error
-;   Corrupts registers:
-;       AX, CX
-;--------------------------------------------------------------------
-.StoreDriveName:
-    push    ds
-    push    si
-    push    di
+;
+; Store Drive Name
+;       
+    push    ds                          ; Preserve RAMVARS
+    push    si                          ; Preserve SI for call to GetTotalSectorCount...
 
-    push    es
+    push    es                          ; ES copied to DS
     pop     ds
+
     add     si, BYTE ATA1.strModel      ; DS:SI now points drive name
     lea     di, [bx+BOOTNFO.szDrvName]  ; ES:DI now points to name destination
@@ -74 +43 @@
     loop    .CopyNextWord
     xor     ax, ax                      ; Zero AX and clear CF
-    stosb                               ; Terminate with NULL
+    stosw                               ; Terminate with NULL
 
-    pop     di
     pop     si
     pop     ds
+
+;
+; Store Sector Count
+;
+    call    AtaID_GetTotalSectorCountToBXDXAXfromAtaInfoInESSI
+
+    stosw
+    xchg    ax, dx
+    stosw
+    xchg    ax, bx
+    stosw
+
+    pop     bx
+        
     ret
 
-
+        
 ;--------------------------------------------------------------------
 ; Finds BOOTNFO for drive and returns total sector count.
@@ -87 +69 @@
 ; BootInfo_GetTotalSectorCount
 ;   Parameters:
-;       DL:     Drive number
-;       DS:     RAMVARS segment
+;       DS:DI:      DPT Pointer
 ;   Returns:
 ;       BX:DX:AX:   48-bit sector count
@@ -97 +78 @@
 BootInfo_GetTotalSectorCount:
     push    ds
-    call    BootInfo_GetOffsetToBX
+    call    BootInfo_ConvertDPTtoBX
     LOAD_BDA_SEGMENT_TO ds, ax
     mov     ax, [bx+BOOTNFO.twSectCnt]
@@ -107 +88 @@
 
 ;--------------------------------------------------------------------
-; Returns offset to BOOTNFO for wanted drive.
+; Returns offset to BOOTNFO based on DPT pointer.
 ;
-; BootInfo_GetOffsetToBX
+; BootInfo_ConvertDPTtoBX
 ;   Parameters:
-;       DL:     Drive number
-;       DS:     RAMVARS segment
+;       DS:DI:  DPT Pointer
 ;   Returns:
 ;       BX:     Offset to BOOTNFO struct
@@ -119 +99 @@
 ;--------------------------------------------------------------------
 ALIGN JUMP_ALIGN
-BootInfo_GetOffsetToBX:
-    mov     bl, dl                      ; Copy drive number to BL
-    mov     al, BOOTNFO_size            ; Size of struct
-    sub     bl, [RAMVARS.bFirstDrv]     ; Drive number to index
-    mul     bl                          ; AX = Offset inside BOOTNFO array
-    add     ax, BOOTVARS.rgBootNfo      ; Add offset to BOOTNFO array
-    xchg    bx, ax                      ; Move result to BX
-    ret
+BootInfo_ConvertDPTtoBX:
+    mov     ax, di
+    sub     ax, RAMVARS_size                ; subtract off base of DPTs
+    mov     bl, DPT_BOOTNFO_SIZE_MULTIPLIER ; BOOTNFO's are a whole number multiple of DPT size
+    mul     bl                              
+    add     ax, BOOTVARS.rgBootNfo          ; add base of BOOTNFO
+    xchg    ax, bx
+    ret