Library for f2c. (part 1 of 2)

Obtained from: netlib.att.com

1 files changed, 96 insertions, 0 deletions

diff --git a/lib/libI77/backspace.c b/lib/libI77/backspace.c
new file mode 100644
index 0000000..4213424
--- /dev/null
+++ b/lib/libI77/backspace.c
@@ -0,0 +1,96 @@
+#include "f2c.h"
+#include "fio.h"
+#ifdef KR_headers
+integer f_back(a) alist *a;
+#else
+integer f_back(alist *a)
+#endif
+{	unit *b;
+	int i, n, ndec;
+#ifdef MSDOS
+	int j, k;
+	long w, z;
+#endif
+	long x, y;
+	char buf[32];
+	if(a->aunit >= MXUNIT || a->aunit < 0)
+		err(a->aerr,101,"backspace")
+	b= &f__units[a->aunit];
+	if(b->useek==0) err(a->aerr,106,"backspace")
+	if(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(b->ufd);
+		y = x % b->url;
+		if(y == 0) x--;
+		x /= b->url;
+		x *= b->url;
+		(void) fseek(b->ufd,x,SEEK_SET);
+		return(0);
+	}
+
+	if(b->ufmt==0)
+	{	(void) fseek(b->ufd,-(long)sizeof(int),SEEK_CUR);
+		(void) fread((char *)&n,sizeof(int),1,b->ufd);
+		(void) fseek(b->ufd,-(long)n-2*sizeof(int),SEEK_CUR);
+		return(0);
+	}
+#ifdef MSDOS
+	w = -1;
+#endif
+	for(ndec = 2;; ndec = 1)
+	{
+		y = x=ftell(b->ufd);
+		if(x<sizeof(buf)) x=0;
+		else x -= sizeof(buf);
+		(void) fseek(b->ufd,x,SEEK_SET);
+		n=fread(buf,1,(int)(y-x), b->ufd);
+		for(i=n-ndec;i>=0;i--)
+		{
+			if(buf[i]!='\n') continue;
+#ifdef MSDOS
+			for(j = k = 0; j <= i; j++)
+				if (buf[j] == '\n')
+					k++;
+			fseek(b->ufd,x,SEEK_SET);
+			do {
+				if (getc(b->ufd) == '\n') {
+					--k;
+					if ((z = ftell(b->ufd)) >= y) {
+						if (w == -1)
+							goto break2;
+						break;
+						}
+					w = z;
+					}
+				} while(k > 0);
+			fseek(b->ufd, w, SEEK_SET);
+#else
+			fseek(b->ufd,(long)(i+1-n),SEEK_CUR);
+#endif
+			return(0);
+		}
+#ifdef MSDOS
+ break2:
+#endif
+		if(x==0)
+			{
+			(void) fseek(b->ufd, 0L, SEEK_SET);
+			return(0);
+			}
+		else if(n<=0) err(a->aerr,(EOF),"backspace")
+		(void) fseek(b->ufd, x, SEEK_SET);
+	}
+}