Bell 32V development

Work on file usr/src/libc/gen/atof.c

Co-Authored-By: John Reiser <jfr@research.uucp>
Synthesized-from: 32v

diff --git a/usr/src/libc/gen/atof.c b/usr/src/libc/gen/atof.c
new file mode 100644 (file)
index 0000000..2818907
--- /dev/null
+++ b/usr/src/libc/gen/atof.c
@@ -0,0 +1,49 @@
+union {
+       short foo0[4];
+       double big;
+} bar0 /* = {0x5c80,0,0,0} */ ; /* 2**56 as double floating point */
+union {
+       short foo1[4];
+       double huge;
+} bar1 /* = {0x8000,0,0,0} */ ; /* reserved operand */
+
+double atof(p) register char *p; {
+register double exp,val;
+register char c; register int dpdig;
+int scale; char sign,esign;
+
+abort(); /* THE REAL ROUTINE IS atofo.s !!!!! */
+while ((c= *p++)==' ');        /* skip leading spaces */
+sign=0;
+if (c=='-') ++sign;    /* mark negative */
+else if (c=='+') ;     /* ignore plus */
+else --p;              /* get back on track */
+
+val=0; dpdig=0;
+/* true value is aproximately  ((-1)**sign) * val * (10 ** dpdig) */
+while ((c= *p++)<='9' && c>='0')
+       if(val<bar0.big) {val *= 10; val += c-'0';}
+       else ++dpdig;
+if (c=='.')
+       while ((c= *p++)<='9' && c>='0')
+               if(val<bar0.big) {--dpdig; val *= 10; val += c-'0';}
+if (sign) val = -val; /* sign has been taken care of, if  val  in range */
+scale=0;
+if (c=='E' || c=='e') {/* scale factor */
+       esign=0;
+       if ((c= *p++)=='-') ++esign;
+       else if (c=='+');
+       else --p;
+       while ((c= *p++)<='9' && c>='0') {scale *= 10; scale += c-'0';}
+       if (esign) scale = -scale;
+}
+dpdig += scale;
+if (dpdig==0) return(val);
+esign=0; if (dpdig<0) {++esign; dpdig = -dpdig;}
+if (dpdig>38) if (esign) return(0); else return(sign? -bar1.huge : bar1.huge);
+exp=1; while (dpdig) {
+       if (dpdig==21) {exp *= 1.0e+21; break;}
+       exp *= 10; --dpdig;
+}
+if (esign) return(val/exp); return(val*exp);
+}