mirror of
https://github.com/86Box/86Box.git
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0f035b42ea
Made ATAPI derived from SCSI. Added proper S/G emulation for SCSI DMA. Added SCSI CD-ROM emulation, preserving all the former ATAPI commands as well.
128 lines
2.7 KiB
C
128 lines
2.7 KiB
C
/* Copyright holders: SA1988
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see COPYING for more details
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*/
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/*Scatter/Gather emulation*/
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#include <stdlib.h>
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#include <string.h>
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#include "ibm.h"
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#include "scattergather.h"
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static uint8_t *SegmentBufferGet(SGBUF *SegmentBuf, uint32_t Data)
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{
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uint32_t DataSize;
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uint8_t *Buffer;
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if (SegmentBuf->SegmentIndex == SegmentBuf->SegmentNum
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&& !SegmentBuf->SegmentLeft)
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{
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Data = 0;
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return NULL;
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}
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DataSize = MIN(Data, SegmentBuf->SegmentLeft);
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Buffer = SegmentBuf->SegmentPtrCur;
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SegmentBuf->SegmentLeft -= Data;
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if (!SegmentBuf->SegmentLeft)
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{
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SegmentBuf->SegmentIndex++;
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if (SegmentBuf->SegmentIndex < SegmentBuf->SegmentNum)
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{
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SegmentBuf->SegmentPtrCur = SegmentBuf->SegmentPtr[SegmentBuf->SegmentIndex].Address;
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SegmentBuf->SegmentLeft = SegmentBuf->SegmentPtr[SegmentBuf->SegmentIndex].Length;
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}
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Data = DataSize;
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}
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else
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SegmentBuf->SegmentPtrCur = (uint8_t *)SegmentBuf->SegmentPtrCur + DataSize;
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return Buffer;
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}
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uint8_t *SegmentBufferGetNextSegment(SGBUF *SegmentBuf, uint32_t Segment)
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{
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if (!Segment)
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Segment = SegmentBuf->SegmentLeft;
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return SegmentBufferGet(SegmentBuf, Segment);
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}
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uint32_t SegmentBufferCopy(SGBUF *SegmentDst, SGBUF *SegmentSrc, uint32_t Copy)
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{
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uint32_t Left = Copy;
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while (Left)
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{
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uint32_t ThisCopy = MIN(MIN(SegmentDst->SegmentLeft, Left), SegmentSrc->SegmentLeft);
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if (!ThisCopy)
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break;
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uint32_t Tmp = ThisCopy;
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uint8_t *BufDst = SegmentBufferGet(SegmentDst, Tmp);
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uint8_t *BufSrc = SegmentBufferGet(SegmentSrc, Tmp);
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memcpy(BufSrc, BufDst, ThisCopy);
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BufDst += ThisCopy;
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BufSrc -= ThisCopy;
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Left -= ThisCopy;
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}
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return Copy - Left;
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}
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uint32_t SegmentBufferCopyFromBuf(SGBUF *SegmentBuf, uint8_t *BufSrc, uint32_t Copy)
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{
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uint32_t Left = Copy;
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while (Left)
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{
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uint32_t ThisCopy = Left;
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uint8_t *BufDst = SegmentBufferGet(SegmentBuf, ThisCopy);
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if (!ThisCopy)
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break;
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BufDst += ThisCopy;
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Left -= ThisCopy;
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BufSrc = (void *)((uintptr_t)BufSrc + ThisCopy);
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}
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return Copy - Left;
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}
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uint32_t SegmentBufferAdvance(SGBUF *SegmentBuf, uint32_t Advance)
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{
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uint32_t Left = Advance;
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while (Left)
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{
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uint32_t ThisAdvance = Left;
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SegmentBufferGet(SegmentBuf, ThisAdvance);
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if (!ThisAdvance)
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break;
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Left -= ThisAdvance;
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}
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return Advance - Left;
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}
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void SegmentBufferInit(SGBUF *SegmentBuf, const SGSEG *SegmentPtr, uint32_t Segments)
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{
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SegmentBuf->SegmentPtr = SegmentPtr;
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SegmentBuf->SegmentNum = (unsigned)Segments;
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SegmentBuf->SegmentIndex = 0;
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if (Segments && SegmentPtr)
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{
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SegmentBuf->SegmentPtrCur = SegmentPtr[0].Address;
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SegmentBuf->SegmentLeft = SegmentPtr[0].Length;
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}
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else
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{
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SegmentBuf->SegmentPtrCur = NULL;
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SegmentBuf->SegmentLeft = 0;
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}
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} |