60 lines
1.4 KiB
C
60 lines
1.4 KiB
C
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/***
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*swab.c - block copy, while swapping even/odd bytes
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*
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* Copyright (c) 1989-2001, Microsoft Corporation. All rights reserved.
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*
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*Purpose:
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* This module contains the routine _swab() which swaps the odd/even
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* bytes of words during a block copy.
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*
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*Revision History:
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* 06-02-89 PHG module created, based on asm version
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* 03-06-90 GJF Fixed calling type, added #include <cruntime.h> and
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* fixed copyright. Also, cleaned up the formatting a
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* bit.
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* 09-27-90 GJF New-style function declarators.
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* 01-21-91 GJF ANSI naming.
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* 04-06-93 SKS Replace _CRTAPI* with _cdecl
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*
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*******************************************************************************/
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#include <cruntime.h>
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#include <stdlib.h>
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/***
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*void _swab(srcptr, dstptr, nbytes) - swap ODD/EVEN bytes during word move
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*
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*Purpose:
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* This routine copys a block of words and swaps the odd and even
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* bytes. nbytes must be > 0, otherwise nothing is copied. If
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* nbytes is odd, then only (nbytes-1) bytes are copied.
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*
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*Entry:
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* srcptr = pointer to the source block
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* dstptr = pointer to the destination block
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* nbytes = number of bytes to swap
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*
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*Returns:
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* None.
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*
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*Exceptions:
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*
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*******************************************************************************/
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void __cdecl _swab (
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char *src,
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char *dest,
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int nbytes
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)
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{
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char b1, b2;
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while (nbytes > 1) {
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b1 = *src++;
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b2 = *src++;
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*dest++ = b2;
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*dest++ = b1;
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nbytes -= 2;
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}
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}
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