| 1 | ; Project name : XTIDE Universal BIOS
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| 2 | ; Description : Functions for preparing data buffer for transfer.
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| 3 |
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| 4 | ; Section containing code
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| 5 | SECTION .text
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| 6 |
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| 7 | ;---------------------------------------------------------------------
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| 8 | ; PrepareBuffer_ToESSIforOldInt13hTransfer
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| 9 | ; Parameters:
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| 10 | ; AL: Number of sectors to transfer
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| 11 | ; SS:BP: Ptr to IDEPACK
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| 12 | ; Parameters on INTPACK:
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| 13 | ; ES:BX: Ptr to data buffer
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| 14 | ; Returns:
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| 15 | ; ES:SI: Ptr to normalized data buffer
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| 16 | ; Exits INT 13h if error
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| 17 | ; Corrupts registers:
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| 18 | ; BX
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| 19 | ;--------------------------------------------------------------------
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| 20 | ALIGN JUMP_ALIGN
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| 21 | PrepareBuffer_ToESSIforOldInt13hTransfer:
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| 22 | ; Normalize buffer pointer
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| 23 | mov bx, [bp+IDEPACK.intpack+INTPACK.bx] ; Load offset
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| 24 | mov si, bx
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| 25 | eSHR_IM bx, 4 ; Divide offset by 16
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| 26 | add bx, [bp+IDEPACK.intpack+INTPACK.es]
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| 27 | mov es, bx ; Segment normalized
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| 28 | and si, BYTE 0Fh ; Offset normalized
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| 29 |
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| 30 | ; Check if valid number of sectors
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| 31 | test al, al
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| 32 | js SHORT .CheckZeroOffsetFor128Sectors
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| 33 | jz SHORT .InvalidNumberOfSectorsRequested
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| 34 | ret ; Continue with transfer
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| 35 |
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| 36 | ALIGN JUMP_ALIGN
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| 37 | .CheckZeroOffsetFor128Sectors:
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| 38 | cmp al, 128
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| 39 | ja SHORT .InvalidNumberOfSectorsRequested
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| 40 | mov ah, RET_HD_BOUNDARY
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| 41 | test si, si ; Offset must be zero to xfer 128 sectors
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| 42 | jnz SHORT .CannotAlignPointerProperly
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| 43 | ret ; Continue with transfer
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| 44 |
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| 45 | .InvalidNumberOfSectorsRequested:
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| 46 | mov ah, RET_HD_INVALID
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| 47 | .CannotAlignPointerProperly:
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| 48 | jmp Int13h_ReturnFromHandlerAfterStoringErrorCodeFromAH
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| 49 |
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