54 lines
1.1 KiB
C++
54 lines
1.1 KiB
C++
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#include "stdafx.h"
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#include "SharedMemory.h"
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int CircBuffWrite(BYTE *pbStart, int cbBuff, int obDst, BYTE *pbSrc, int cb)
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{
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// Assumes cb bytes are available and 0 <= obDst <= cbBuff.
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// cb1 is the lesser of number of bytes before the end of the buffer
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// and the number of bytes to write.
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int cb1 = min(cb, cbBuff - obDst);
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if (cb1 > 0)
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{
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memcpy(pbStart + obDst, pbSrc, cb1);
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obDst += cb1;
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cb -= cb1;
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}
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// If there's anything left, then we wrapped around to the
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// beginning of the buffer.
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if (cb > 0)
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{
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memcpy(pbStart, pbSrc + cb1, cb);
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obDst = cb1;
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}
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return obDst;
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}
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int CircBuffRead(BYTE *pbStart, int cbBuff, int obSrc, BYTE *pbDst, int cb)
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{
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// Assumes cb bytes are available and 0 <= obDst <= cbBuff.
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// cb1 is the lesser of number of bytes before the end of the buffer
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// and the number of bytes to write.
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int cb1 = min(cb, cbBuff - (pbDst - pbStart));
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if (cb1 > 0)
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{
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memcpy(pbDst, pbStart + obSrc, cb1);
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obSrc += cb1;
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cb -= cb1;
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}
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// If there's anything left, then we wrapped around to the
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// beginning of the buffer.
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if (cb > 0)
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{
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memcpy(pbDst + cb1, pbStart, cb);
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obSrc = cb1;
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}
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return obSrc;
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}
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