Make improvements

third_party/gdtoa/hexnan.c

@@ -0,0 +1,160 @@
+#include "third_party/gdtoa/gdtoaimp.h"
+
+/* clang-format off */
+/****************************************************************
+
+The author of this software is David M. Gay.
+
+Copyright (C) 2000 by Lucent Technologies
+All Rights Reserved
+
+Permission to use, copy, modify, and distribute this software and
+its documentation for any purpose and without fee is hereby
+granted, provided that the above copyright notice appear in all
+copies and that both that the copyright notice and this
+permission notice and warranty disclaimer appear in supporting
+documentation, and that the name of Lucent or any of its entities
+not be used in advertising or publicity pertaining to
+distribution of the software without specific, written prior
+permission.
+
+LUCENT DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
+INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS.
+IN NO EVENT SHALL LUCENT OR ANY OF ITS ENTITIES BE LIABLE FOR ANY
+SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER
+IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
+ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
+THIS SOFTWARE.
+
+****************************************************************/
+
+/* Please send bug reports to David M. Gay (dmg at acm dot org,
+ * with " at " changed at "@" and " dot " changed to ".").	*/
+
+ static void
+#ifdef KR_headers
+L_shift(x, x1, i) ULong *x; ULong *x1; int i;
+#else
+L_shift(ULong *x, ULong *x1, int i)
+#endif
+{
+	int j;
+
+	i = 8 - i;
+	i <<= 2;
+	j = ULbits - i;
+	do {
+		*x |= x[1] << j;
+		x[1] >>= i;
+		} while(++x < x1);
+	}
+
+ int
+#ifdef KR_headers
+hexnan(sp, fpi, x0)
+	CONST char **sp; CONST FPI *fpi; ULong *x0;
+#else
+hexnan( CONST char **sp, CONST FPI *fpi, ULong *x0)
+#endif
+{
+	ULong c, h, *x, *x1, *xe;
+	CONST char *s;
+	int havedig, hd0, i, nbits;
+
+	/**** if (!hexdig['0']) hexdig_init_D2A(); ****/
+	nbits = fpi->nbits;
+	x = x0 + (nbits >> kshift);
+	if (nbits & kmask)
+		x++;
+	*--x = 0;
+	x1 = xe = x;
+	havedig = hd0 = i = 0;
+	s = *sp;
+	/* allow optional initial 0x or 0X */
+	while((c = *(CONST unsigned char*)(s+1)) && c <= ' ') {
+		if (!c)
+			goto retnan;
+		++s;
+		}
+	if (s[1] == '0' && (s[2] == 'x' || s[2] == 'X')
+	 && *(CONST unsigned char*)(s+3) > ' ')
+		s += 2;
+	while((c = *(CONST unsigned char*)++s)) {
+		if (!(h = hexdig[c])) {
+			if (c <= ' ') {
+				if (hd0 < havedig) {
+					if (x < x1 && i < 8)
+						L_shift(x, x1, i);
+					if (x <= x0) {
+						i = 8;
+						continue;
+						}
+					hd0 = havedig;
+					*--x = 0;
+					x1 = x;
+					i = 0;
+					}
+				while((c = *(CONST unsigned char*)(s+1)) <= ' ') {
+					if (!c)
+						goto retnan;
+					++s;
+					}
+				if (s[1] == '0' && (s[2] == 'x' || s[2] == 'X')
+				 && *(CONST unsigned char*)(s+3) > ' ')
+					s += 2;
+				continue;
+				}
+			if (/*(*/ c == ')' && havedig) {
+				*sp = s + 1;
+				break;
+				}
+#ifndef GDTOA_NON_PEDANTIC_NANCHECK
+			do {
+				if (/*(*/ c == ')') {
+					*sp = s + 1;
+					goto break2;
+					}
+				} while((c = *++s));
+#endif
+ retnan:
+			return STRTOG_NaN;
+			}
+		havedig++;
+		if (++i > 8) {
+			if (x <= x0)
+				continue;
+			i = 1;
+			*--x = 0;
+			}
+		*x = (*x << 4) | (h & 0xf);
+		}
+#ifndef GDTOA_NON_PEDANTIC_NANCHECK
+ break2:
+#endif
+	if (!havedig)
+		return STRTOG_NaN;
+	if (x < x1 && i < 8)
+		L_shift(x, x1, i);
+	if (x > x0) {
+		x1 = x0;
+		do *x1++ = *x++;
+			while(x <= xe);
+		do *x1++ = 0;
+			while(x1 <= xe);
+		}
+	else {
+		/* truncate high-order word if necessary */
+		if ( (i = nbits & (ULbits-1)) !=0)
+			*xe &= ((ULong)0xffffffff) >> (ULbits - i);
+		}
+	for(x1 = xe;; --x1) {
+		if (*x1 != 0)
+			break;
+		if (x1 == x0) {
+			*x1 = 1;
+			break;
+			}
+		}
+	return STRTOG_NaNbits;
+	}