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/* ----------------------------------------------------------------------- *
*
* Copyright 2004 H. Peter Anvin - All Rights Reserved
*
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation
* files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use,
* copy, modify, merge, publish, distribute, sublicense, and/or
* sell copies of the Software, and to permit persons to whom
* the Software is furnished to do so, subject to the following
* conditions:
*
* The above copyright notice and this permission notice shall
* be included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*
* ----------------------------------------------------------------------- */
/*
* read.c
*
* Reading from a file
*/
#include <errno.h>
#include <string.h>
#include <com32.h>
#include <minmax.h>
#include "file.h"
ssize_t __file_read(struct file_info *fp, void *buf, size_t count)
{
com32sys_t ireg, oreg;
char *bufp = buf;
size_t n = 0;
size_t ncopy;
memset(&ireg, 0, sizeof ireg);
ireg.eax.w[0] = 0x0007; /* Read file */
ireg.esi.w[0] = OFFS(__com32.cs_bounce);
ireg.es = SEG(__com32.cs_bounce);
while ( count ) {
if ( fp->i.nbytes == 0 ) {
if ( fp->i.offset >= fp->i.length || !fp->i.filedes )
return n; /* As good as it gets... */
ireg.esi.w[0] = fp->i.filedes;
ireg.ecx.w[0] = MAXBLOCK >> fp->i.blocklg2;
__intcall(0x22, &ireg, &oreg);
if ( oreg.eflags.l & EFLAGS_CF ) {
errno = EIO;
return -1;
}
fp->i.filedes = ireg.esi.w[0];
fp->i.nbytes = min(fp->i.length-fp->i.offset, (unsigned)MAXBLOCK);
fp->i.datap = fp->i.buf;
memcpy(fp->i.buf, __com32.cs_bounce, fp->i.nbytes);
}
ncopy = min(count, fp->i.nbytes);
memcpy(bufp, fp->i.datap, ncopy);
n += ncopy;
bufp += ncopy;
count -= ncopy;
fp->i.datap += ncopy;
fp->i.offset += ncopy;
fp->i.nbytes -= ncopy;
}
return n;
}
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