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Diffstat (limited to 'gcc-4.7/libiberty/floatformat.c')
| -rw-r--r-- | gcc-4.7/libiberty/floatformat.c | 775 |
1 files changed, 775 insertions, 0 deletions
diff --git a/gcc-4.7/libiberty/floatformat.c b/gcc-4.7/libiberty/floatformat.c new file mode 100644 index 000000000..1116c6311 --- /dev/null +++ b/gcc-4.7/libiberty/floatformat.c @@ -0,0 +1,775 @@ +/* IEEE floating point support routines, for GDB, the GNU Debugger. + Copyright 1991, 1994, 1999, 2000, 2003, 2005, 2006, 2010 + Free Software Foundation, Inc. + +This file is part of GDB. + +This program is free software; you can redistribute it and/or modify +it under the terms of the GNU General Public License as published by +the Free Software Foundation; either version 2 of the License, or +(at your option) any later version. + +This program is distributed in the hope that it will be useful, +but WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +GNU General Public License for more details. + +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., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, 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 + +/* On some platforms, <float.h> provides DBL_QNAN. */ +#ifdef STDC_HEADERS +#include <float.h> +#endif + +#include "ansidecl.h" +#include "libiberty.h" +#include "floatformat.h" + +#ifndef INFINITY +#ifdef HUGE_VAL +#define INFINITY HUGE_VAL +#else +#define INFINITY (1.0 / 0.0) +#endif +#endif + +#ifndef NAN +#ifdef DBL_QNAN +#define NAN DBL_QNAN +#else +#define NAN (0.0 / 0.0) +#endif +#endif + +static int mant_bits_set (const struct floatformat *, const unsigned char *); +static unsigned long get_field (const unsigned char *, + enum floatformat_byteorders, + unsigned int, + unsigned int, + unsigned int); +static int floatformat_always_valid (const struct floatformat *fmt, + const void *from); + +static int +floatformat_always_valid (const struct floatformat *fmt ATTRIBUTE_UNUSED, + const void *from ATTRIBUTE_UNUSED) +{ + return 1; +} + +/* The odds that CHAR_BIT will be anything but 8 are low enough that I'm not + going to bother with trying to muck around with whether it is defined in + a system header, what we do if not, etc. */ +#define FLOATFORMAT_CHAR_BIT 8 + +/* floatformats for IEEE half, single and double, big and little endian. */ +const struct floatformat floatformat_ieee_half_big = +{ + floatformat_big, 16, 0, 1, 5, 15, 31, 6, 10, + floatformat_intbit_no, + "floatformat_ieee_half_big", + floatformat_always_valid, + NULL +}; +const struct floatformat floatformat_ieee_half_little = +{ + floatformat_little, 16, 0, 1, 5, 15, 31, 6, 10, + floatformat_intbit_no, + "floatformat_ieee_half_little", + floatformat_always_valid, + NULL +}; +const struct floatformat floatformat_ieee_single_big = +{ + floatformat_big, 32, 0, 1, 8, 127, 255, 9, 23, + floatformat_intbit_no, + "floatformat_ieee_single_big", + floatformat_always_valid, + NULL +}; +const struct floatformat floatformat_ieee_single_little = +{ + floatformat_little, 32, 0, 1, 8, 127, 255, 9, 23, + floatformat_intbit_no, + "floatformat_ieee_single_little", + floatformat_always_valid, + NULL +}; +const struct floatformat floatformat_ieee_double_big = +{ + floatformat_big, 64, 0, 1, 11, 1023, 2047, 12, 52, + floatformat_intbit_no, + "floatformat_ieee_double_big", + floatformat_always_valid, + NULL +}; +const struct floatformat floatformat_ieee_double_little = +{ + floatformat_little, 64, 0, 1, 11, 1023, 2047, 12, 52, + floatformat_intbit_no, + "floatformat_ieee_double_little", + floatformat_always_valid, + NULL +}; + +/* floatformat for IEEE double, little endian byte order, with big endian word + ordering, as on the ARM. */ + +const struct floatformat floatformat_ieee_double_littlebyte_bigword = +{ + floatformat_littlebyte_bigword, 64, 0, 1, 11, 1023, 2047, 12, 52, + floatformat_intbit_no, + "floatformat_ieee_double_littlebyte_bigword", + floatformat_always_valid, + NULL +}; + +/* floatformat for VAX. Not quite IEEE, but close enough. */ + +const struct floatformat floatformat_vax_f = +{ + floatformat_vax, 32, 0, 1, 8, 129, 0, 9, 23, + floatformat_intbit_no, + "floatformat_vax_f", + floatformat_always_valid, + NULL +}; +const struct floatformat floatformat_vax_d = +{ + floatformat_vax, 64, 0, 1, 8, 129, 0, 9, 55, + floatformat_intbit_no, + "floatformat_vax_d", + floatformat_always_valid, + NULL +}; +const struct floatformat floatformat_vax_g = +{ + floatformat_vax, 64, 0, 1, 11, 1025, 0, 12, 52, + floatformat_intbit_no, + "floatformat_vax_g", + floatformat_always_valid, + NULL +}; + +static int floatformat_i387_ext_is_valid (const struct floatformat *fmt, + const void *from); + +static int +floatformat_i387_ext_is_valid (const struct floatformat *fmt, const void *from) +{ + /* In the i387 double-extended format, if the exponent is all ones, + then the integer bit must be set. If the exponent is neither 0 + nor ~0, the intbit must also be set. Only if the exponent is + zero can it be zero, and then it must be zero. */ + unsigned long exponent, int_bit; + const unsigned char *ufrom = (const unsigned char *) from; + + exponent = get_field (ufrom, fmt->byteorder, fmt->totalsize, + fmt->exp_start, fmt->exp_len); + int_bit = get_field (ufrom, fmt->byteorder, fmt->totalsize, + fmt->man_start, 1); + + if ((exponent == 0) != (int_bit == 0)) + return 0; + else + return 1; +} + +const struct floatformat floatformat_i387_ext = +{ + floatformat_little, 80, 0, 1, 15, 0x3fff, 0x7fff, 16, 64, + floatformat_intbit_yes, + "floatformat_i387_ext", + floatformat_i387_ext_is_valid, + NULL +}; +const struct floatformat floatformat_m68881_ext = +{ + /* Note that the bits from 16 to 31 are unused. */ + floatformat_big, 96, 0, 1, 15, 0x3fff, 0x7fff, 32, 64, + floatformat_intbit_yes, + "floatformat_m68881_ext", + floatformat_always_valid, + NULL +}; +const struct floatformat floatformat_i960_ext = +{ + /* Note that the bits from 0 to 15 are unused. */ + floatformat_little, 96, 16, 17, 15, 0x3fff, 0x7fff, 32, 64, + floatformat_intbit_yes, + "floatformat_i960_ext", + floatformat_always_valid, + NULL +}; +const struct floatformat floatformat_m88110_ext = +{ + floatformat_big, 80, 0, 1, 15, 0x3fff, 0x7fff, 16, 64, + floatformat_intbit_yes, + "floatformat_m88110_ext", + floatformat_always_valid, + NULL +}; +const struct floatformat floatformat_m88110_harris_ext = +{ + /* Harris uses raw format 128 bytes long, but the number is just an ieee + double, and the last 64 bits are wasted. */ + floatformat_big,128, 0, 1, 11, 0x3ff, 0x7ff, 12, 52, + floatformat_intbit_no, + "floatformat_m88110_ext_harris", + floatformat_always_valid, + NULL +}; +const struct floatformat floatformat_arm_ext_big = +{ + /* Bits 1 to 16 are unused. */ + floatformat_big, 96, 0, 17, 15, 0x3fff, 0x7fff, 32, 64, + floatformat_intbit_yes, + "floatformat_arm_ext_big", + floatformat_always_valid, + NULL +}; +const struct floatformat floatformat_arm_ext_littlebyte_bigword = +{ + /* Bits 1 to 16 are unused. */ + floatformat_littlebyte_bigword, 96, 0, 17, 15, 0x3fff, 0x7fff, 32, 64, + floatformat_intbit_yes, + "floatformat_arm_ext_littlebyte_bigword", + floatformat_always_valid, + NULL +}; +const struct floatformat floatformat_ia64_spill_big = +{ + floatformat_big, 128, 0, 1, 17, 65535, 0x1ffff, 18, 64, + floatformat_intbit_yes, + "floatformat_ia64_spill_big", + floatformat_always_valid, + NULL +}; +const struct floatformat floatformat_ia64_spill_little = +{ + floatformat_little, 128, 0, 1, 17, 65535, 0x1ffff, 18, 64, + floatformat_intbit_yes, + "floatformat_ia64_spill_little", + floatformat_always_valid, + NULL +}; +const struct floatformat floatformat_ia64_quad_big = +{ + floatformat_big, 128, 0, 1, 15, 16383, 0x7fff, 16, 112, + floatformat_intbit_no, + "floatformat_ia64_quad_big", + floatformat_always_valid, + NULL +}; +const struct floatformat floatformat_ia64_quad_little = +{ + floatformat_little, 128, 0, 1, 15, 16383, 0x7fff, 16, 112, + floatformat_intbit_no, + "floatformat_ia64_quad_little", + floatformat_always_valid, + NULL +}; + +static int +floatformat_ibm_long_double_is_valid (const struct floatformat *fmt, + const void *from) +{ + const unsigned char *ufrom = (const unsigned char *) from; + const struct floatformat *hfmt = fmt->split_half; + long top_exp, bot_exp; + int top_nan = 0; + + top_exp = get_field (ufrom, hfmt->byteorder, hfmt->totalsize, + hfmt->exp_start, hfmt->exp_len); + bot_exp = get_field (ufrom + 8, hfmt->byteorder, hfmt->totalsize, + hfmt->exp_start, hfmt->exp_len); + + if ((unsigned long) top_exp == hfmt->exp_nan) + top_nan = mant_bits_set (hfmt, ufrom); + + /* A NaN is valid with any low part. */ + if (top_nan) + return 1; + + /* An infinity, zero or denormal requires low part 0 (positive or + negative). */ + if ((unsigned long) top_exp == hfmt->exp_nan || top_exp == 0) + { + if (bot_exp != 0) + return 0; + + return !mant_bits_set (hfmt, ufrom + 8); + } + + /* The top part is now a finite normal value. The long double value + is the sum of the two parts, and the top part must equal the + result of rounding the long double value to nearest double. Thus + the bottom part must be <= 0.5ulp of the top part in absolute + value, and if it is < 0.5ulp then the long double is definitely + valid. */ + if (bot_exp < top_exp - 53) + return 1; + if (bot_exp > top_exp - 53 && bot_exp != 0) + return 0; + if (bot_exp == 0) + { + /* The bottom part is 0 or denormal. Determine which, and if + denormal the first two set bits. */ + int first_bit = -1, second_bit = -1, cur_bit; + for (cur_bit = 0; (unsigned int) cur_bit < hfmt->man_len; cur_bit++) + if (get_field (ufrom + 8, hfmt->byteorder, hfmt->totalsize, + hfmt->man_start + cur_bit, 1)) + { + if (first_bit == -1) + first_bit = cur_bit; + else + { + second_bit = cur_bit; + break; + } + } + /* Bottom part 0 is OK. */ + if (first_bit == -1) + return 1; + /* The real exponent of the bottom part is -first_bit. */ + if (-first_bit < top_exp - 53) + return 1; + if (-first_bit > top_exp - 53) + return 0; + /* The bottom part is at least 0.5ulp of the top part. For this + to be OK, the bottom part must be exactly 0.5ulp (i.e. no + more bits set) and the top part must have last bit 0. */ + if (second_bit != -1) + return 0; + return !get_field (ufrom, hfmt->byteorder, hfmt->totalsize, + hfmt->man_start + hfmt->man_len - 1, 1); + } + else + { + /* The bottom part is at least 0.5ulp of the top part. For this + to be OK, it must be exactly 0.5ulp (i.e. no explicit bits + set) and the top part must have last bit 0. */ + if (get_field (ufrom, hfmt->byteorder, hfmt->totalsize, + hfmt->man_start + hfmt->man_len - 1, 1)) + return 0; + return !mant_bits_set (hfmt, ufrom + 8); + } +} + +const struct floatformat floatformat_ibm_long_double = +{ + floatformat_big, 128, 0, 1, 11, 1023, 2047, 12, 52, + floatformat_intbit_no, + "floatformat_ibm_long_double", + floatformat_ibm_long_double_is_valid, + &floatformat_ieee_double_big +}; + + +#ifndef min +#define min(a, b) ((a) < (b) ? (a) : (b)) +#endif + +/* Return 1 if any bits are explicitly set in the mantissa of UFROM, + format FMT, 0 otherwise. */ +static int +mant_bits_set (const struct floatformat *fmt, const unsigned char *ufrom) +{ + unsigned int mant_bits, mant_off; + int mant_bits_left; + + mant_off = fmt->man_start; + mant_bits_left = fmt->man_len; + 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) + return 1; + + mant_off += mant_bits; + mant_bits_left -= mant_bits; + } + return 0; +} + +/* Extract a field which starts at START and is LEN bits long. DATA and + TOTAL_LEN are the thing we are extracting it from, in byteorder ORDER. */ +static unsigned long +get_field (const unsigned char *data, enum floatformat_byteorders order, + unsigned int total_len, unsigned int start, unsigned int len) +{ + unsigned long result = 0; + unsigned int cur_byte; + int lo_bit, hi_bit, cur_bitshift = 0; + int nextbyte = (order == floatformat_little) ? 1 : -1; + + /* Start is in big-endian bit order! Fix that first. */ + start = total_len - (start + len); + + /* Start at the least significant part of the field. */ + if (order == floatformat_little) + cur_byte = start / FLOATFORMAT_CHAR_BIT; + else + cur_byte = (total_len - start - 1) / FLOATFORMAT_CHAR_BIT; + + lo_bit = start % FLOATFORMAT_CHAR_BIT; + hi_bit = min (lo_bit + len, FLOATFORMAT_CHAR_BIT); + + do + { + unsigned int shifted = *(data + cur_byte) >> lo_bit; + unsigned int bits = hi_bit - lo_bit; + unsigned int mask = (1 << bits) - 1; + result |= (shifted & mask) << cur_bitshift; + len -= bits; + cur_bitshift += bits; + cur_byte += nextbyte; + lo_bit = 0; + hi_bit = min (len, FLOATFORMAT_CHAR_BIT); + } + while (len != 0); + + return result; +} + +/* Convert from FMT to a double. + FROM is the address of the extended float. + Store the double in *TO. */ + +void +floatformat_to_double (const struct floatformat *fmt, + const void *from, double *to) +{ + const unsigned char *ufrom = (const unsigned char *) from; + double dto; + long exponent; + unsigned long mant; + unsigned int mant_bits, mant_off; + int mant_bits_left; + int special_exponent; /* It's a NaN, denorm or zero */ + + /* Split values are not handled specially, since the top half has + the correctly rounded double value (in the only supported case of + split values). */ + + exponent = get_field (ufrom, fmt->byteorder, fmt->totalsize, + fmt->exp_start, fmt->exp_len); + + /* 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_bits_set (fmt, ufrom); + + /* On certain systems (such as GNU/Linux), the use of the + INFINITY macro below may generate a warning that can not be + silenced due to a bug in GCC (PR preprocessor/11931). The + preprocessor fails to recognise the __extension__ keyword in + conjunction with the GNU/C99 extension for hexadecimal + floating point constants and will issue a warning when + compiling with -pedantic. */ + 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; + dto = 0.0; + + special_exponent = exponent == 0 || (unsigned long) exponent == fmt->exp_nan; + + /* Don't bias zero's, denorms or NaNs. */ + if (!special_exponent) + exponent -= fmt->exp_bias; + + /* Build the result algebraically. Might go infinite, underflow, etc; + who cares. */ + + /* If this format uses a hidden bit, explicitly add it in now. Otherwise, + increment the exponent by one to account for the integer bit. */ + + if (!special_exponent) + { + if (fmt->intbit == floatformat_intbit_no) + dto = ldexp (1.0, exponent); + else + exponent++; + } + + while (mant_bits_left > 0) + { + mant_bits = min (mant_bits_left, 32); + + mant = get_field (ufrom, fmt->byteorder, fmt->totalsize, + mant_off, mant_bits); + + /* Handle denormalized numbers. FIXME: What should we do for + non-IEEE formats? */ + if (special_exponent && 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; + } + + /* Negate it if negative. */ + if (get_field (ufrom, fmt->byteorder, fmt->totalsize, fmt->sign_start, 1)) + dto = -dto; + *to = dto; +} + +static void put_field (unsigned char *, enum floatformat_byteorders, + unsigned int, + unsigned int, + unsigned int, + unsigned long); + +/* Set a field which starts at START and is LEN bits long. DATA and + TOTAL_LEN are the thing we are extracting it from, in byteorder ORDER. */ +static void +put_field (unsigned char *data, enum floatformat_byteorders order, + unsigned int total_len, unsigned int start, unsigned int len, + unsigned long stuff_to_put) +{ + unsigned int cur_byte; + int lo_bit, hi_bit; + int nextbyte = (order == floatformat_little) ? 1 : -1; + + /* Start is in big-endian bit order! Fix that first. */ + start = total_len - (start + len); + + /* Start at the least significant part of the field. */ + if (order == floatformat_little) + cur_byte = start / FLOATFORMAT_CHAR_BIT; + else + cur_byte = (total_len - start - 1) / FLOATFORMAT_CHAR_BIT; + + lo_bit = start % FLOATFORMAT_CHAR_BIT; + hi_bit = min (lo_bit + len, FLOATFORMAT_CHAR_BIT); + + do + { + unsigned char *byte_ptr = data + cur_byte; + unsigned int bits = hi_bit - lo_bit; + unsigned int mask = ((1 << bits) - 1) << lo_bit; + *byte_ptr = (*byte_ptr & ~mask) | ((stuff_to_put << lo_bit) & mask); + stuff_to_put >>= bits; + len -= bits; + cur_byte += nextbyte; + lo_bit = 0; + hi_bit = min (len, FLOATFORMAT_CHAR_BIT); + } + while (len != 0); +} + +/* The converse: convert the double *FROM to an extended float + and store where TO points. Neither FROM nor TO have any alignment + restrictions. */ + +void +floatformat_from_double (const struct floatformat *fmt, + const double *from, void *to) +{ + double dfrom; + int exponent; + double mant; + unsigned int mant_bits, mant_off; + int mant_bits_left; + unsigned char *uto = (unsigned char *) to; + + dfrom = *from; + memset (uto, 0, fmt->totalsize / FLOATFORMAT_CHAR_BIT); + + /* Split values are not handled specially, since a bottom half of + zero is correct for any value representable as double (in the + only supported case of split values). */ + + /* 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) + { + /* 0.0. */ + return; + } + + if (dfrom != dfrom) + { + /* 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 irrelevant. */ + put_field (uto, fmt->byteorder, fmt->totalsize, fmt->man_start, + 32, 1); + return; + } + + if (dfrom + 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; + } + + mant = frexp (dfrom, &exponent); + 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; + while (mant_bits_left > 0) + { + unsigned long mant_long; + mant_bits = mant_bits_left < 32 ? mant_bits_left : 32; + + mant *= 4294967296.0; + mant_long = (unsigned long)mant; + mant -= mant_long; + + /* 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 + && exponent + fmt->exp_bias - 1 > 0) + { + mant_long &= 0x7fffffff; + mant_bits -= 1; + } + else if (mant_bits < 32) + { + /* The bits we want are in the most significant MANT_BITS bits of + mant_long. Move them to the least significant. */ + mant_long >>= 32 - mant_bits; + } + + put_field (uto, fmt->byteorder, fmt->totalsize, + mant_off, mant_bits, mant_long); + mant_off += mant_bits; + mant_bits_left -= mant_bits; + } +} + +/* Return non-zero iff the data at FROM is a valid number in format FMT. */ + +int +floatformat_is_valid (const struct floatformat *fmt, const void *from) +{ + return fmt->is_valid (fmt, from); +} + + +#ifdef IEEE_DEBUG + +#include <stdio.h> + +/* This is to be run on a host which uses IEEE floating point. */ + +void +ieee_test (double n) +{ + double result; + + floatformat_to_double (&floatformat_ieee_double_little, &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_little, &n, &result); + if ((n != result && (! isnan (n) || ! isnan (result))) + || (n < 0 && result >= 0) + || (n >= 0 && result < 0)) + printf ("Differ(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. */ + { + long double ex = *(long double *)exten; + if (ex != n) + printf ("Differ(from vs. extended): %.20g\n", n); + } +#endif +} + +int +main (void) +{ + 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 |