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[FREELDR] Adapt FAT helper code for the future base address change (#7785)

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Daniel Victor 2025-03-14 18:29:36 -03:00
parent 1bcc8f147b
commit a8b186e5fc
1 changed files with 27 additions and 7 deletions
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34
boot/freeldr/freeldr/arch/realmode/fathelp.inc
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@ -14,9 +14,13 @@
#define BiosCHSDriveSizeHigh 6
#define BiosCHSDriveSizeLow 8
#define BiosCHSDriveSize 8
#define ReadSectorsOffset 10
#define ReadClusterOffset 12
#define PutCharsOffset 14
#define ReadSectorsOffset 12
#define ReadClusterOffset 16
#define PutCharsOffset 20
#define ReadSectors dword ptr ss:[bp-ReadSectorsOffset]
#define ReadCluster dword ptr ss:[bp-ReadClusterOffset]
#define PutChars dword ptr ss:[bp-PutCharsOffset]
#define OEMName 3
#define BytesPerSector 11
@ -65,8 +69,8 @@ FatHelperEntryPoint:
push ax
/* Display "Loading FreeLoader..." message */
mov si, offset msgLoading
call word ptr [bp-PutCharsOffset]
mov si, offset msgLoading - FREELDR_BASE
call CS_PutChars
call ReadFatIntoMemory
@ -92,7 +96,7 @@ LoadFile3:
push ax
xor bx,bx // Load ROSLDR starting at 0000:8000h
push es
call word ptr [bp-ReadClusterOffset]
call ReadCluster
pop es
xor bx,bx
@ -133,7 +137,7 @@ ReadFatIntoMemory:
mov bx, HEX(7000)
mov es,bx
xor bx,bx
call word ptr [bp-ReadSectorsOffset]
call ReadSectors
ret
@ -216,6 +220,22 @@ IsFat12_2:
IsFat12_Done:
ret
CS_PutChars:
/* Save necessary registers */
push ax
push ds
/* Prepare ds before PutChars call */
mov ax, cs
mov ds, ax
/* Display the message */
call PutChars
/* Restore necessary registers and return */
pop ds
pop ax
ret
msgLoading:
.ascii "Loading FreeLoader...", CR, LF, NUL