diff options
Diffstat (limited to 'gas/config/atof-ieee.c')
| -rw-r--r-- | gas/config/atof-ieee.c | 696 |
1 files changed, 696 insertions, 0 deletions
diff --git a/gas/config/atof-ieee.c b/gas/config/atof-ieee.c new file mode 100644 index 0000000..d586e3a --- /dev/null +++ b/gas/config/atof-ieee.c @@ -0,0 +1,696 @@ +/* atof_ieee.c - turn a Flonum into an IEEE floating point number + Copyright (C) 1987, 92, 93, 94, 95, 96, 97, 1998 + Free Software Foundation, Inc. + + This file is part of GAS, the GNU Assembler. + + GAS 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, or (at your option) + any later version. + + GAS 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 GAS; see the file COPYING. If not, write to the Free + Software Foundation, 59 Temple Place - Suite 330, Boston, MA + 02111-1307, USA. */ + +#include "as.h" + +/* Flonums returned here. */ +extern FLONUM_TYPE generic_floating_point_number; + +static int next_bits PARAMS ((int)); +static void unget_bits PARAMS ((int)); +static void make_invalid_floating_point_number PARAMS ((LITTLENUM_TYPE *)); + +extern const char EXP_CHARS[]; +/* Precision in LittleNums. */ +/* Don't count the gap in the m68k extended precision format. */ +#define MAX_PRECISION (5) +#define F_PRECISION (2) +#define D_PRECISION (4) +#define X_PRECISION (5) +#define P_PRECISION (5) + +/* Length in LittleNums of guard bits. */ +#define GUARD (2) + +static const unsigned long mask[] = +{ + 0x00000000, + 0x00000001, + 0x00000003, + 0x00000007, + 0x0000000f, + 0x0000001f, + 0x0000003f, + 0x0000007f, + 0x000000ff, + 0x000001ff, + 0x000003ff, + 0x000007ff, + 0x00000fff, + 0x00001fff, + 0x00003fff, + 0x00007fff, + 0x0000ffff, + 0x0001ffff, + 0x0003ffff, + 0x0007ffff, + 0x000fffff, + 0x001fffff, + 0x003fffff, + 0x007fffff, + 0x00ffffff, + 0x01ffffff, + 0x03ffffff, + 0x07ffffff, + 0x0fffffff, + 0x1fffffff, + 0x3fffffff, + 0x7fffffff, + 0xffffffff, +}; + + +static int bits_left_in_littlenum; +static int littlenums_left; +static LITTLENUM_TYPE *littlenum_pointer; + +static int +next_bits (number_of_bits) + int number_of_bits; +{ + int return_value; + + if (!littlenums_left) + return (0); + if (number_of_bits >= bits_left_in_littlenum) + { + return_value = mask[bits_left_in_littlenum] & *littlenum_pointer; + number_of_bits -= bits_left_in_littlenum; + return_value <<= number_of_bits; + + if (--littlenums_left) + { + bits_left_in_littlenum = LITTLENUM_NUMBER_OF_BITS - number_of_bits; + --littlenum_pointer; + return_value |= (*littlenum_pointer >> bits_left_in_littlenum) & mask[number_of_bits]; + } + } + else + { + bits_left_in_littlenum -= number_of_bits; + return_value = mask[number_of_bits] & (*littlenum_pointer >> bits_left_in_littlenum); + } + return (return_value); +} + +/* Num had better be less than LITTLENUM_NUMBER_OF_BITS */ +static void +unget_bits (num) + int num; +{ + if (!littlenums_left) + { + ++littlenum_pointer; + ++littlenums_left; + bits_left_in_littlenum = num; + } + else if (bits_left_in_littlenum + num > LITTLENUM_NUMBER_OF_BITS) + { + bits_left_in_littlenum = num - (LITTLENUM_NUMBER_OF_BITS - bits_left_in_littlenum); + ++littlenum_pointer; + ++littlenums_left; + } + else + bits_left_in_littlenum += num; +} + +static void +make_invalid_floating_point_number (words) + LITTLENUM_TYPE *words; +{ + as_bad (_("cannot create floating-point number")); + words[0] = (LITTLENUM_TYPE) ((unsigned) -1) >> 1; /* Zero the leftmost bit */ + words[1] = (LITTLENUM_TYPE) -1; + words[2] = (LITTLENUM_TYPE) -1; + words[3] = (LITTLENUM_TYPE) -1; + words[4] = (LITTLENUM_TYPE) -1; + words[5] = (LITTLENUM_TYPE) -1; +} + +/************************************************************************\ + * Warning: this returns 16-bit LITTLENUMs. It is up to the caller * + * to figure out any alignment problems and to conspire for the * + * bytes/word to be emitted in the right order. Bigendians beware! * + * * +\************************************************************************/ + +/* Note that atof-ieee always has X and P precisions enabled. it is up + to md_atof to filter them out if the target machine does not support + them. */ + +/* Returns pointer past text consumed. */ +char * +atof_ieee (str, what_kind, words) + char *str; /* Text to convert to binary. */ + char what_kind; /* 'd', 'f', 'g', 'h' */ + LITTLENUM_TYPE *words; /* Build the binary here. */ +{ + /* Extra bits for zeroed low-order bits. The 1st MAX_PRECISION are + zeroed, the last contain flonum bits. */ + static LITTLENUM_TYPE bits[MAX_PRECISION + MAX_PRECISION + GUARD]; + char *return_value; + /* Number of 16-bit words in the format. */ + int precision; + long exponent_bits; + FLONUM_TYPE save_gen_flonum; + + /* We have to save the generic_floating_point_number because it + contains storage allocation about the array of LITTLENUMs where + the value is actually stored. We will allocate our own array of + littlenums below, but have to restore the global one on exit. */ + save_gen_flonum = generic_floating_point_number; + + return_value = str; + generic_floating_point_number.low = bits + MAX_PRECISION; + generic_floating_point_number.high = NULL; + generic_floating_point_number.leader = NULL; + generic_floating_point_number.exponent = 0; + generic_floating_point_number.sign = '\0'; + + /* Use more LittleNums than seems necessary: the highest flonum may + have 15 leading 0 bits, so could be useless. */ + + memset (bits, '\0', sizeof (LITTLENUM_TYPE) * MAX_PRECISION); + + switch (what_kind) + { + case 'f': + case 'F': + case 's': + case 'S': + precision = F_PRECISION; + exponent_bits = 8; + break; + + case 'd': + case 'D': + case 'r': + case 'R': + precision = D_PRECISION; + exponent_bits = 11; + break; + + case 'x': + case 'X': + case 'e': + case 'E': + precision = X_PRECISION; + exponent_bits = 15; + break; + + case 'p': + case 'P': + + precision = P_PRECISION; + exponent_bits = -1; + break; + + default: + make_invalid_floating_point_number (words); + return (NULL); + } + + generic_floating_point_number.high + = generic_floating_point_number.low + precision - 1 + GUARD; + + if (atof_generic (&return_value, ".", EXP_CHARS, + &generic_floating_point_number)) + { + make_invalid_floating_point_number (words); + return (NULL); + } + gen_to_words (words, precision, exponent_bits); + + /* Restore the generic_floating_point_number's storage alloc (and + everything else). */ + generic_floating_point_number = save_gen_flonum; + + return return_value; +} + +/* Turn generic_floating_point_number into a real float/double/extended. */ +int +gen_to_words (words, precision, exponent_bits) + LITTLENUM_TYPE *words; + int precision; + long exponent_bits; +{ + int return_value = 0; + + long exponent_1; + long exponent_2; + long exponent_3; + long exponent_4; + int exponent_skippage; + LITTLENUM_TYPE word1; + LITTLENUM_TYPE *lp; + LITTLENUM_TYPE *words_end; + + words_end = words + precision; +#ifdef TC_M68K + if (precision == X_PRECISION) + /* On the m68k the extended precision format has a gap of 16 bits + between the exponent and the mantissa. */ + words_end++; +#endif + + if (generic_floating_point_number.low > generic_floating_point_number.leader) + { + /* 0.0e0 seen. */ + if (generic_floating_point_number.sign == '+') + words[0] = 0x0000; + else + words[0] = 0x8000; + memset (&words[1], '\0', + (words_end - words - 1) * sizeof (LITTLENUM_TYPE)); + return (return_value); + } + + /* NaN: Do the right thing */ + if (generic_floating_point_number.sign == 0) + { + if (precision == F_PRECISION) + { + words[0] = 0x7fff; + words[1] = 0xffff; + } + else if (precision == X_PRECISION) + { +#ifdef TC_M68K + words[0] = 0x7fff; + words[1] = 0; + words[2] = 0xffff; + words[3] = 0xffff; + words[4] = 0xffff; + words[5] = 0xffff; +#else /* ! TC_M68K */ +#ifdef TC_I386 + words[0] = 0xffff; + words[1] = 0xc000; + words[2] = 0; + words[3] = 0; + words[4] = 0; +#else /* ! TC_I386 */ + abort (); +#endif /* ! TC_I386 */ +#endif /* ! TC_M68K */ + } + else + { + words[0] = 0x7fff; + words[1] = 0xffff; + words[2] = 0xffff; + words[3] = 0xffff; + } + return return_value; + } + else if (generic_floating_point_number.sign == 'P') + { + /* +INF: Do the right thing */ + if (precision == F_PRECISION) + { + words[0] = 0x7f80; + words[1] = 0; + } + else if (precision == X_PRECISION) + { +#ifdef TC_M68K + words[0] = 0x7fff; + words[1] = 0; + words[2] = 0; + words[3] = 0; + words[4] = 0; + words[5] = 0; +#else /* ! TC_M68K */ +#ifdef TC_I386 + words[0] = 0x7fff; + words[1] = 0x8000; + words[2] = 0; + words[3] = 0; + words[4] = 0; +#else /* ! TC_I386 */ + abort (); +#endif /* ! TC_I386 */ +#endif /* ! TC_M68K */ + } + else + { + words[0] = 0x7ff0; + words[1] = 0; + words[2] = 0; + words[3] = 0; + } + return (return_value); + } + else if (generic_floating_point_number.sign == 'N') + { + /* Negative INF */ + if (precision == F_PRECISION) + { + words[0] = 0xff80; + words[1] = 0x0; + } + else if (precision == X_PRECISION) + { +#ifdef TC_M68K + words[0] = 0xffff; + words[1] = 0; + words[2] = 0; + words[3] = 0; + words[4] = 0; + words[5] = 0; +#else /* ! TC_M68K */ +#ifdef TC_I386 + words[0] = 0xffff; + words[1] = 0x8000; + words[2] = 0; + words[3] = 0; + words[4] = 0; +#else /* ! TC_I386 */ + abort (); +#endif /* ! TC_I386 */ +#endif /* ! TC_M68K */ + } + else + { + words[0] = 0xfff0; + words[1] = 0x0; + words[2] = 0x0; + words[3] = 0x0; + } + return (return_value); + } + /* + * The floating point formats we support have: + * Bit 15 is sign bit. + * Bits 14:n are excess-whatever exponent. + * Bits n-1:0 (if any) are most significant bits of fraction. + * Bits 15:0 of the next word(s) are the next most significant bits. + * + * So we need: number of bits of exponent, number of bits of + * mantissa. + */ + bits_left_in_littlenum = LITTLENUM_NUMBER_OF_BITS; + littlenum_pointer = generic_floating_point_number.leader; + littlenums_left = (1 + + generic_floating_point_number.leader + - generic_floating_point_number.low); + /* Seek (and forget) 1st significant bit */ + for (exponent_skippage = 0; !next_bits (1); ++exponent_skippage);; + exponent_1 = (generic_floating_point_number.exponent + + generic_floating_point_number.leader + + 1 + - generic_floating_point_number.low); + /* Radix LITTLENUM_RADIX, point just higher than + generic_floating_point_number.leader. */ + exponent_2 = exponent_1 * LITTLENUM_NUMBER_OF_BITS; + /* Radix 2. */ + exponent_3 = exponent_2 - exponent_skippage; + /* Forget leading zeros, forget 1st bit. */ + exponent_4 = exponent_3 + ((1 << (exponent_bits - 1)) - 2); + /* Offset exponent. */ + + lp = words; + + /* Word 1. Sign, exponent and perhaps high bits. */ + word1 = ((generic_floating_point_number.sign == '+') + ? 0 + : (1 << (LITTLENUM_NUMBER_OF_BITS - 1))); + + /* Assume 2's complement integers. */ + if (exponent_4 <= 0) + { + int prec_bits; + int num_bits; + + unget_bits (1); + num_bits = -exponent_4; + prec_bits = LITTLENUM_NUMBER_OF_BITS * precision - (exponent_bits + 1 + num_bits); +#ifdef TC_I386 + if (precision == X_PRECISION && exponent_bits == 15) + { + /* On the i386 a denormalized extended precision float is + shifted down by one, effectively decreasing the exponent + bias by one. */ + prec_bits -= 1; + num_bits += 1; + } +#endif + + if (num_bits >= LITTLENUM_NUMBER_OF_BITS - exponent_bits) + { + /* Bigger than one littlenum */ + num_bits -= (LITTLENUM_NUMBER_OF_BITS - 1) - exponent_bits; + *lp++ = word1; + if (num_bits + exponent_bits + 1 >= precision * LITTLENUM_NUMBER_OF_BITS) + { + /* Exponent overflow */ + make_invalid_floating_point_number (words); + return (return_value); + } +#ifdef TC_M68K + if (precision == X_PRECISION && exponent_bits == 15) + *lp++ = 0; +#endif + while (num_bits >= LITTLENUM_NUMBER_OF_BITS) + { + num_bits -= LITTLENUM_NUMBER_OF_BITS; + *lp++ = 0; + } + if (num_bits) + *lp++ = next_bits (LITTLENUM_NUMBER_OF_BITS - (num_bits)); + } + else + { + if (precision == X_PRECISION && exponent_bits == 15) + { + *lp++ = word1; +#ifdef TC_M68K + *lp++ = 0; +#endif + *lp++ = next_bits (LITTLENUM_NUMBER_OF_BITS - num_bits); + } + else + { + word1 |= next_bits ((LITTLENUM_NUMBER_OF_BITS - 1) - (exponent_bits + num_bits)); + *lp++ = word1; + } + } + while (lp < words_end) + *lp++ = next_bits (LITTLENUM_NUMBER_OF_BITS); + + /* Round the mantissa up, but don't change the number */ + if (next_bits (1)) + { + --lp; + if (prec_bits > LITTLENUM_NUMBER_OF_BITS) + { + int n = 0; + int tmp_bits; + + n = 0; + tmp_bits = prec_bits; + while (tmp_bits > LITTLENUM_NUMBER_OF_BITS) + { + if (lp[n] != (LITTLENUM_TYPE) - 1) + break; + --n; + tmp_bits -= LITTLENUM_NUMBER_OF_BITS; + } + if (tmp_bits > LITTLENUM_NUMBER_OF_BITS || (lp[n] & mask[tmp_bits]) != mask[tmp_bits]) + { + unsigned long carry; + + for (carry = 1; carry && (lp >= words); lp--) + { + carry = *lp + carry; + *lp = carry; + carry >>= LITTLENUM_NUMBER_OF_BITS; + } + } + else + { + /* This is an overflow of the denormal numbers. We + need to forget what we have produced, and instead + generate the smallest normalized number. */ + lp = words; + word1 = ((generic_floating_point_number.sign == '+') + ? 0 + : (1 << (LITTLENUM_NUMBER_OF_BITS - 1))); + word1 |= (1 + << ((LITTLENUM_NUMBER_OF_BITS - 1) + - exponent_bits)); + *lp++ = word1; + while (lp < words_end) + *lp++ = 0; + } + } + else if ((*lp & mask[prec_bits]) != mask[prec_bits]) + *lp += 1; + } + + return return_value; + } + else if ((unsigned long) exponent_4 >= mask[exponent_bits]) + { + /* + * Exponent overflow. Lose immediately. + */ + + /* + * We leave return_value alone: admit we read the + * number, but return a floating exception + * because we can't encode the number. + */ + make_invalid_floating_point_number (words); + return return_value; + } + else + { + word1 |= (exponent_4 << ((LITTLENUM_NUMBER_OF_BITS - 1) - exponent_bits)) + | next_bits ((LITTLENUM_NUMBER_OF_BITS - 1) - exponent_bits); + } + + *lp++ = word1; + + /* X_PRECISION is special: on the 68k, it has 16 bits of zero in the + middle. Either way, it is then followed by a 1 bit. */ + if (exponent_bits == 15 && precision == X_PRECISION) + { +#ifdef TC_M68K + *lp++ = 0; +#endif + *lp++ = (1 << (LITTLENUM_NUMBER_OF_BITS - 1) + | next_bits (LITTLENUM_NUMBER_OF_BITS - 1)); + } + + /* The rest of the words are just mantissa bits. */ + while (lp < words_end) + *lp++ = next_bits (LITTLENUM_NUMBER_OF_BITS); + + if (next_bits (1)) + { + unsigned long carry; + /* + * Since the NEXT bit is a 1, round UP the mantissa. + * The cunning design of these hidden-1 floats permits + * us to let the mantissa overflow into the exponent, and + * it 'does the right thing'. However, we lose if the + * highest-order bit of the lowest-order word flips. + * Is that clear? + */ + + /* #if (sizeof(carry)) < ((sizeof(bits[0]) * BITS_PER_CHAR) + 2) + Please allow at least 1 more bit in carry than is in a LITTLENUM. + We need that extra bit to hold a carry during a LITTLENUM carry + propagation. Another extra bit (kept 0) will assure us that we + don't get a sticky sign bit after shifting right, and that + permits us to propagate the carry without any masking of bits. + #endif */ + for (carry = 1, lp--; carry && (lp >= words); lp--) + { + carry = *lp + carry; + *lp = carry; + carry >>= LITTLENUM_NUMBER_OF_BITS; + } + if (precision == X_PRECISION && exponent_bits == 15) + { + /* Extended precision numbers have an explicit integer bit + that we may have to restore. */ + if (lp == words) + { +#ifdef TC_M68K + /* On the m68k there is a gap of 16 bits. We must + explicitly propagate the carry into the exponent. */ + words[0] += words[1]; + words[1] = 0; + lp++; +#endif + /* Put back the integer bit. */ + lp[1] |= 1 << (LITTLENUM_NUMBER_OF_BITS - 1); + } + } + if ((word1 ^ *words) & (1 << (LITTLENUM_NUMBER_OF_BITS - 1))) + { + /* We leave return_value alone: admit we read the + * number, but return a floating exception + * because we can't encode the number. + */ + *words &= ~(1 << (LITTLENUM_NUMBER_OF_BITS - 1)); + /* make_invalid_floating_point_number (words); */ + /* return return_value; */ + } + } + return (return_value); +} + +#if 0 /* unused */ +/* This routine is a real kludge. Someone really should do it better, + but I'm too lazy, and I don't understand this stuff all too well + anyway. (JF) */ +static void +int_to_gen (x) + long x; +{ + char buf[20]; + char *bufp; + + sprintf (buf, "%ld", x); + bufp = &buf[0]; + if (atof_generic (&bufp, ".", EXP_CHARS, &generic_floating_point_number)) + as_bad (_("Error converting number to floating point (Exponent overflow?)")); +} +#endif + +#ifdef TEST +char * +print_gen (gen) + FLONUM_TYPE *gen; +{ + FLONUM_TYPE f; + LITTLENUM_TYPE arr[10]; + double dv; + float fv; + static char sbuf[40]; + + if (gen) + { + f = generic_floating_point_number; + generic_floating_point_number = *gen; + } + gen_to_words (&arr[0], 4, 11); + memcpy (&dv, &arr[0], sizeof (double)); + sprintf (sbuf, "%x %x %x %x %.14G ", arr[0], arr[1], arr[2], arr[3], dv); + gen_to_words (&arr[0], 2, 8); + memcpy (&fv, &arr[0], sizeof (float)); + sprintf (sbuf + strlen (sbuf), "%x %x %.12g\n", arr[0], arr[1], fv); + + if (gen) + { + generic_floating_point_number = f; + } + + return (sbuf); +} + +#endif + +/* end of atof-ieee.c */ |