127 lines
2.4 KiB
C
127 lines
2.4 KiB
C
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/*
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* mio.c - Colin Kelley 1-18-87
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* routines to emulate temporary file handling with memory instead
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*
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* rjm 980212 - changed to use memcpy rather than bcopy
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*/
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#include <stdio.h>
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#include <string.h>
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#include <stdlib.h>
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#define UNUSED(var) ((void) var)
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#define MALLOC_SIZE 10000
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#define JUNK_FPTR stdin /* junk ptr to return (unused) */
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static unsigned char *mhead; /* pointer to start of malloc()d area */
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static unsigned char *mend; /* pointer to current (just beyond) EOF*/
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static unsigned char *mptr; /* pointer to current position */
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static unsigned int msize; /* size of chunk mhead points to */
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FILE *mfopen(char *filename,char *mode)
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{
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UNUSED (filename);
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UNUSED (mode);
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if ((mhead = malloc(MALLOC_SIZE)) == NULL) {
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msize = 0;
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return (NULL);
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}
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msize = MALLOC_SIZE;
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mend = mptr = mhead;
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return (JUNK_FPTR); /* not used */
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}
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int mfclose(FILE *f)
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{
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UNUSED (f);
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if (mhead) {
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free(mhead);
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return (0);
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}
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else
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return (-1);
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}
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int mfputc(unsigned int c,FILE *f)
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{
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unsigned char *p;
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UNUSED (f);
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while (mptr >= mhead + msize) {
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if ((p = realloc(mhead,msize+MALLOC_SIZE)) == (unsigned char *)-1) {
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fputs("mio: out of memory\n",stderr);
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return (-1);
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}
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else {
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msize += MALLOC_SIZE;
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mptr = (unsigned char *) (p + (unsigned int)(mptr - mhead));
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mhead = p;
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}
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}
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*mptr = c & 255;
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mend = ++mptr;
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return c;
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}
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int mfgetc(FILE *f)
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{
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UNUSED (f);
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if (mptr >= mend) /* no characters left */
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return (-1);
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else
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return (*mptr++);
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}
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int mfseek(FILE *f,long loc,int origin)
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{
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UNUSED (f);
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if (origin != 0) {
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fputs("mseek() only implemented with 0 origin",stderr);
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return (-1);
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}
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mptr = mhead + loc;
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return (0);
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}
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int mfread(char *ptr, unsigned int size, unsigned int nitems, FILE *f)
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{
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unsigned int i = 0;
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UNUSED (f);
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while (i < nitems) {
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if ((mptr + size) > mend)
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break;
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memcpy(ptr,mptr,size);
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ptr += size;
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mptr += size;
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i++;
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}
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return (i);
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}
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int mfwrite(char *ptr, int size, int nitems, FILE *f)
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{
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int i = 0;
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unsigned char *p;
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UNUSED (f);
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while (i < nitems) {
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while (mptr + size >= mhead + msize) {
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if ((p = realloc(mhead,msize+MALLOC_SIZE)) == (unsigned char *)-1){
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fputs("mio: out of memory\n",stderr);
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return (-1);
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}
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else {
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msize += MALLOC_SIZE;
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mptr = (unsigned char *) (p + (unsigned int)(mptr - mhead));
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mhead = p;
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}
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}
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if ((mptr + size) > mhead + msize)
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break;
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memcpy(mend,ptr,size);
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ptr += size;
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mend += size;
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mptr = mend;
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}
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return (i);
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}
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