freebsd-nq/lib/libI77/backspace.c
Joerg Wunsch c3ad4b4583 Update to the most recent version. Among other things, this also solves
the function naming problem for complex double function i've recently
aksed for in -committers.  (The recently committed rev 1.5 of proc.c
was actually also part of this update.)

Should the mailing lists come to an agreement that f2c better belongs
into the ports, this could be done nevertheless.  For the time being,
we've at least got a current version now.

Thanks, Steve!

Submitted by:	Steve Kargl <sgk@troutmask.apl.washington.edu>
1999-02-03 17:23:49 +00:00

70 lines
1.2 KiB
C

#include "f2c.h"
#include "fio.h"
#ifdef KR_headers
integer f_back(a) alist *a;
#else
integer f_back(alist *a)
#endif
{ unit *b;
long v, w, x, y, z;
uiolen n;
FILE *f;
f__curunit = b = &f__units[a->aunit]; /* curunit for error messages */
if(a->aunit >= MXUNIT || a->aunit < 0)
err(a->aerr,101,"backspace")
if(b->useek==0) err(a->aerr,106,"backspace")
if((f = b->ufd) == NULL) {
fk_open(1, 1, a->aunit);
return(0);
}
if(b->uend==1)
{ b->uend=0;
return(0);
}
if(b->uwrt) {
(void) t_runc(a);
if (f__nowreading(b))
err(a->aerr,errno,"backspace")
}
if(b->url>0)
{
x=ftell(f);
y = x % b->url;
if(y == 0) x--;
x /= b->url;
x *= b->url;
(void) fseek(f,x,SEEK_SET);
return(0);
}
if(b->ufmt==0)
{ fseek(f,-(long)sizeof(uiolen),SEEK_CUR);
fread((char *)&n,sizeof(uiolen),1,f);
fseek(f,-(long)n-2*sizeof(uiolen),SEEK_CUR);
return(0);
}
w = x = ftell(f);
z = 0;
loop:
while(x) {
x -= x < 64 ? x : 64;
fseek(f,x,SEEK_SET);
for(y = x; y < w; y++) {
if (getc(f) != '\n')
continue;
v = ftell(f);
if (v == w) {
if (z)
goto break2;
goto loop;
}
z = v;
}
err(a->aerr,(EOF),"backspace")
}
break2:
fseek(f, z, SEEK_SET);
return 0;
}