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fastread.c
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fastread.c
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#include<stdio.h>
#include<stdlib.h>
#include<string.h>
// I think I used this in something for CreditShop. May have to rewrite.
typedef struct iter {
FILE* f;
char* buf;
int buflen;
int bufcount;
int prior_final;
int xind;
unsigned int flags;
char delim;
} iter;
unsigned int _iter_MALLOC_BUF = 0x1;
unsigned int _iter_FINAL_READ = 0x2;
unsigned int _iter_LAST_LINE = 0x4;
char* _iter_next_buffer(iter*);
iter* alloc_iter()
{ return (iter*)malloc(sizeof(iter)); }
iter* init_iter(iter* it, FILE* f, char* buf, int buflen, char delim)
{
it->flags = 0;
it->f = f;
it->buflen = buflen;
it->bufcount = 0;
if (buf == 0) {
it->buf = (buf ? buf : (char*)malloc(sizeof(char)*buflen+1));
it->flags |= _iter_MALLOC_BUF;
}
else
it->buf = buf;
it->buf[it->buflen] = 0;
it->prior_final = 0;
it->xind = 0;
it->delim = delim;
// Initial buffer read and first line setup.
_iter_next_buffer(it);
return it;
}
iter* new_iter(FILE* f, char* buf, int buflen, char delim)
{ return init_iter(alloc_iter(),f,buf,buflen,delim); }
iter* del_iter(iter* it)
{
//fprintf(stderr,"%08x\n",it->flags);
if ((it->flags & _iter_MALLOC_BUF) && it->buf)
free(it->buf);
return it;
}
void free_iter(iter* it)
{ free(del_iter(it)); }
char* _iter_next_buffer(iter* it)
{
if (feof(it->f)) {
// Reached EOF, last buffer read.
it->flags |= _iter_FINAL_READ;
return 0;
}
//fprintf(stderr,"_iter_next_buffer: %i,%i,%08x\n",it->bufcount,it->xind,it->flags);
// NOTE: This iterator depends on is buflen being longer than the largest line.
char* buf = it->buf;
//int prior_final = it->prior_final;
int prior_final = it->xind;
// Fill beginning of buffer with buf[prior_final:].
//fprintf(stderr,"sliding over: [%s]\n",&buf[prior_final]);
int i=0;
if (prior_final > 0) {
int tail_len = it->buflen - prior_final;
for (i=0; i < tail_len; ++i)
buf[i] = buf[i+prior_final];
}
// Read in the rest.
int count = 0;
count = fread(&buf[i], sizeof(buf[0]), it->buflen-i, it->f);
if (count < it->buflen-i) {
// Is this redundant?
//fprintf(stderr,"FINAL READ!\n");
it->flags |= _iter_FINAL_READ;
// Enforce a double zero, or *a* zero?... on the start of the next buffer?
if (i+count <= it->buflen)
buf[i+count] = 0;
}
it->xind = 0;
it->bufcount += 1;
//fprintf(stderr,"buf: %s\n",buf);
return buf;
}
char* iter_next(iter* it)
{
if (it->flags & _iter_LAST_LINE)
return 0;
char* buf = it->buf;
int buflen = it->buflen;
//fprintf(stderr,"xind: %i\n",it->xind);
// Double zeros. We need to force a double-zero on the final buffer read.
if (!buf[it->xind] || it->xind >= it->buflen) {
if (it->flags & _iter_FINAL_READ) {
// Reached the end of everything, I guess...
it->flags |= _iter_LAST_LINE;
return 0;
}
else {
// Buffer reset trailing line to beginning, so gotta do again.
//fprintf(stderr,"Vrap daggle.\n");
_iter_next_buffer(it);
return iter_next(it);
}
}
char* c = &buf[it->xind];
int i;
for (i=it->xind; buf[i] && i < buflen; ++i) {
////fprintf(stderr,"%i,%c\n",i,buf[i]);
if (buf[i] == '\n') {
buf[i] = 0;
break;
}
}
++i;
if (i >= buflen && buf[i-1] != '\n') {
//fprintf(stderr,"This one, here... but with i,xind,buflen: %i, %i, %i\n",i,it->xind,buflen);
_iter_next_buffer(it);
return iter_next(it);
}
it->xind = i;
//fprintf(stderr,"setting xind to: %i\n",i);
// At this point, the returned string is ready to go. Just need to set xind.
return c;
}
int iter_has_next(iter* it)
{
if (it->flags & _iter_LAST_LINE)
return 0;
return 1;
}
int main(int argc, const char** argv)
{
//fprintf(stderr,"%s\n","Who even knows the even what?");
FILE* f;
const char* fname = 0;
char* buf;
if (argc > 1)
fname = argv[1];
f = fopen(fname,"r");
int buflen = 120;
iter* fiter = new_iter(f,0,buflen,'\n');
buf = fiter->buf;
int h = -1;
char* s = 0;
char c[1024];
char n = 0;
int i = 0;
do {
//fprintf(stderr,"n: %i, %i, %08x\n",n,fiter->bufcount,fiter->flags);
s = iter_next(fiter);
printf("%s\n",s);
i++;
} while (s && i < 15);
free_iter(fiter);
fclose(f);
return 0;
}