Add original unix v6

source/iolib/cgetc.c

@@ -0,0 +1,31 @@
+# include "ciodec.c"
+char cgetc(fn)
+{
+struct fileps *fp;
+if (nargs() != 1)
+	IEHzap("cgetc  ");
+if (fn <0 || fn >15)
+	IEH3err("cgetc: %d illegal file number",fn);
+fp = &IEH3fpts[fn];
+if (fp == 0 || fp->wrflag > 1)
+	IEH3err("cgetc: %d not open to read",fn);
+if (fp->wrflag == 0)
+	/* file not opened with fopen: try making a buffer */
+	IEH3mbuf (fn, 0);
+if (fp->eoferr > 1)
+	return ('\0');
+if (fp->nchars == 0)
+	 switch (fp->nchars = read(fn, fp->bptr=fp->buff, fp->bsize))
+		{
+		case -1: /* error */
+			if (fp->eoferr == 0)
+				IEH3err("cgetc: error on %d",fn);
+			fp->eoferr = 3;
+			return ('\0');
+		case 0: fp->eoferr = 2;
+			return ('\0');
+		}
+fp->nchars--;
+return (*(fp->bptr++));
+}
+cin 0;