diff options
Diffstat (limited to 'libiberty/floatformat.c')
| -rw-r--r-- | libiberty/floatformat.c | 183 |
1 files changed, 145 insertions, 38 deletions
diff --git a/libiberty/floatformat.c b/libiberty/floatformat.c index daac661..a0f6535 100644 --- a/libiberty/floatformat.c +++ b/libiberty/floatformat.c @@ -17,16 +17,33 @@ You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ +/* This is needed to pick up the NAN macro on some systems. */ +#define _GNU_SOURCE + +#ifdef HAVE_CONFIG_H +#include "config.h" +#endif + +#include <math.h> + +#ifdef HAVE_STRING_H +#include <string.h> +#endif + #include "ansidecl.h" +#include "libiberty.h" #include "floatformat.h" -#include <math.h> /* ldexp */ -#ifdef ANSI_PROTOTYPES -#include <stddef.h> -extern void *memcpy (void *s1, const void *s2, size_t n); -extern void *memset (void *s, int c, size_t n); + +#ifndef INFINITY +#ifdef HUGE_VAL +#define INFINITY HUGE_VAL #else -extern char *memcpy (); -extern char *memset (); +#define INFINITY (1.0 / 0.0) +#endif +#endif + +#ifndef NAN +#define NAN (0.0 / 0.0) #endif static unsigned long get_field PARAMS ((const unsigned char *, @@ -271,9 +288,45 @@ floatformat_to_double (fmt, from, to) exponent = get_field (ufrom, fmt->byteorder, fmt->totalsize, fmt->exp_start, fmt->exp_len); - /* Note that if exponent indicates a NaN, we can't really do anything useful - (not knowing if the host has NaN's, or how to build one). So it will - end up as an infinity or something close; that is OK. */ + + /* If the exponent indicates a NaN, we don't have information to + decide what to do. So we handle it like IEEE, except that we + don't try to preserve the type of NaN. FIXME. */ + if ((unsigned long) exponent == fmt->exp_nan) + { + int nan; + + mant_off = fmt->man_start; + mant_bits_left = fmt->man_len; + nan = 0; + while (mant_bits_left > 0) + { + mant_bits = min (mant_bits_left, 32); + + if (get_field (ufrom, fmt->byteorder, fmt->totalsize, + mant_off, mant_bits) != 0) + { + /* This is a NaN. */ + nan = 1; + break; + } + + mant_off += mant_bits; + mant_bits_left -= mant_bits; + } + + if (nan) + dto = NAN; + else + dto = INFINITY; + + if (get_field (ufrom, fmt->byteorder, fmt->totalsize, fmt->sign_start, 1)) + dto = -dto; + + *to = dto; + + return; + } mant_bits_left = fmt->man_len; mant_off = fmt->man_start; @@ -306,8 +359,18 @@ floatformat_to_double (fmt, from, to) mant = get_field (ufrom, fmt->byteorder, fmt->totalsize, mant_off, mant_bits); - dto += ldexp ((double)mant, exponent - mant_bits); - exponent -= mant_bits; + /* Handle denormalized numbers. FIXME: What should we do for + non-IEEE formats? */ + if (exponent == 0 && mant != 0) + dto += ldexp ((double)mant, + (- fmt->exp_bias + - mant_bits + - (mant_off - fmt->man_start) + + 1)); + else + dto += ldexp ((double)mant, exponent - mant_bits); + if (exponent != 0) + exponent -= mant_bits; mant_off += mant_bits; mant_bits_left -= mant_bits; } @@ -392,33 +455,54 @@ floatformat_from_double (fmt, from, to) int mant_bits_left; unsigned char *uto = (unsigned char *)to; - memcpy (&dfrom, from, sizeof (dfrom)); + dfrom = *from; memset (uto, 0, fmt->totalsize / FLOATFORMAT_CHAR_BIT); + + /* If negative, set the sign bit. */ + if (dfrom < 0) + { + put_field (uto, fmt->byteorder, fmt->totalsize, fmt->sign_start, 1, 1); + dfrom = -dfrom; + } + if (dfrom == 0) - return; /* Result is zero */ + { + /* 0.0. */ + return; + } + if (dfrom != dfrom) { - /* From is NaN */ + /* NaN. */ put_field (uto, fmt->byteorder, fmt->totalsize, fmt->exp_start, fmt->exp_len, fmt->exp_nan); - /* Be sure it's not infinity, but NaN value is irrel */ + /* Be sure it's not infinity, but NaN value is irrelevant. */ put_field (uto, fmt->byteorder, fmt->totalsize, fmt->man_start, 32, 1); return; } - /* If negative, set the sign bit. */ - if (dfrom < 0) + if (dfrom + dfrom == dfrom) { - put_field (uto, fmt->byteorder, fmt->totalsize, fmt->sign_start, 1, 1); - dfrom = -dfrom; + /* This can only happen for an infinite value (or zero, which we + already handled above). */ + put_field (uto, fmt->byteorder, fmt->totalsize, fmt->exp_start, + fmt->exp_len, fmt->exp_nan); + return; } - /* How to tell an infinity from an ordinary number? FIXME-someday */ - mant = frexp (dfrom, &exponent); - put_field (uto, fmt->byteorder, fmt->totalsize, fmt->exp_start, fmt->exp_len, - exponent + fmt->exp_bias - 1); + if (exponent + fmt->exp_bias - 1 > 0) + put_field (uto, fmt->byteorder, fmt->totalsize, fmt->exp_start, + fmt->exp_len, exponent + fmt->exp_bias - 1); + else + { + /* Handle a denormalized number. FIXME: What should we do for + non-IEEE formats? */ + put_field (uto, fmt->byteorder, fmt->totalsize, fmt->exp_start, + fmt->exp_len, 0); + mant = ldexp (mant, exponent + fmt->exp_bias - 1); + } mant_bits_left = fmt->man_len; mant_off = fmt->man_start; @@ -431,12 +515,11 @@ floatformat_from_double (fmt, from, to) mant_long = (unsigned long)mant; mant -= mant_long; - /* If the integer bit is implicit, then we need to discard it. - If we are discarding a zero, we should be (but are not) creating - a denormalized number which means adjusting the exponent - (I think). */ + /* If the integer bit is implicit, and we are not creating a + denormalized number, then we need to discard it. */ if ((unsigned int) mant_bits_left == fmt->man_len - && fmt->intbit == floatformat_intbit_no) + && fmt->intbit == floatformat_intbit_no + && exponent + fmt->exp_bias - 1 > 0) { mant_long &= 0x7fffffff; mant_bits -= 1; @@ -468,6 +551,8 @@ floatformat_is_valid (fmt, from) #ifdef IEEE_DEBUG +#include <stdio.h> + /* This is to be run on a host which uses IEEE floating point. */ void @@ -475,19 +560,31 @@ ieee_test (n) double n; { double result; - char exten[16]; - floatformat_to_double (&floatformat_ieee_double_big, &n, &result); - if (n != result) + floatformat_to_double (&floatformat_ieee_double_little, (char *) &n, + &result); + if ((n != result && (! isnan (n) || ! isnan (result))) + || (n < 0 && result >= 0) + || (n >= 0 && result < 0)) printf ("Differ(to): %.20g -> %.20g\n", n, result); - floatformat_from_double (&floatformat_ieee_double_big, &n, &result); - if (n != result) + + floatformat_from_double (&floatformat_ieee_double_little, &n, + (char *) &result); + if ((n != result && (! isnan (n) || ! isnan (result))) + || (n < 0 && result >= 0) + || (n >= 0 && result < 0)) printf ("Differ(from): %.20g -> %.20g\n", n, result); - floatformat_from_double (&floatformat_m68881_ext, &n, exten); - floatformat_to_double (&floatformat_m68881_ext, exten, &result); - if (n != result) - printf ("Differ(to+from): %.20g -> %.20g\n", n, result); +#if 0 + { + char exten[16]; + + floatformat_from_double (&floatformat_m68881_ext, &n, exten); + floatformat_to_double (&floatformat_m68881_ext, exten, &result); + if (n != result) + printf ("Differ(to+from): %.20g -> %.20g\n", n, result); + } +#endif #if IEEE_DEBUG > 1 /* This is to be run on a host which uses 68881 format. */ @@ -502,12 +599,22 @@ ieee_test (n) int main () { + ieee_test (0.0); ieee_test (0.5); ieee_test (256.0); ieee_test (0.12345); ieee_test (234235.78907234); ieee_test (-512.0); ieee_test (-0.004321); + ieee_test (1.2E-70); + ieee_test (1.2E-316); + ieee_test (4.9406564584124654E-324); + ieee_test (- 4.9406564584124654E-324); + ieee_test (- 0.0); + ieee_test (- INFINITY); + ieee_test (- NAN); + ieee_test (INFINITY); + ieee_test (NAN); return 0; } #endif |