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Diffstat (limited to 'gas/config/atof-ieee.c')
| -rw-r--r-- | gas/config/atof-ieee.c | 511 |
1 files changed, 511 insertions, 0 deletions
diff --git a/gas/config/atof-ieee.c b/gas/config/atof-ieee.c new file mode 100644 index 0000000000..323d4e123b --- /dev/null +++ b/gas/config/atof-ieee.c @@ -0,0 +1,511 @@ +/* atof_ieee.c - turn a Flonum into an IEEE floating point number + Copyright (C) 1987 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 1, 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, 675 Mass Ave, Cambridge, MA 02139, USA. */ + +#include "as.h" + +#ifdef USG +#define bzero(s,n) memset(s,0,n) +#define bcopy(from,to,n) memcpy((to),(from),(n)) +#endif + +extern FLONUM_TYPE generic_floating_point_number; /* Flonums returned here. */ + +#ifndef NULL +#define NULL (0) +#endif + +extern char EXP_CHARS[]; + /* Precision in LittleNums. */ +#define MAX_PRECISION (6) +#define F_PRECISION (2) +#define D_PRECISION (4) +#define X_PRECISION (6) +#define P_PRECISION (6) + + /* Length in LittleNums of guard bits. */ +#define GUARD (2) + +static 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]= ((unsigned)-1)>>1; /* Zero the leftmost bit */ + words[1]= -1; + words[2]= -1; + words[3]= -1; + words[4]= -1; + words[5]= -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. */ + +char * /* Return pointer past text consumed. */ +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. */ +{ + static LITTLENUM_TYPE bits [MAX_PRECISION + MAX_PRECISION + GUARD]; + /* Extra bits for zeroed low-order bits. */ + /* The 1st MAX_PRECISION are zeroed, */ + /* the last contain flonum bits. */ + char * return_value; + int precision; /* Number of 16-bit words in the format. */ + long exponent_bits; + + 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 = NULL; + 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. */ + + bzero (bits, 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)) { + /* as_bad("Error converting floating point number (Exponent overflow?)"); */ + make_invalid_floating_point_number (words); + return NULL; + } + gen_to_words(words, precision, exponent_bits); + 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; + + 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; + bzero (&words[1], sizeof(LITTLENUM_TYPE) * (precision-1)); + 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 { + 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 { + 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 { + 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<1 && exponent_4>=-62) { + 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); + if(precision==X_PRECISION && exponent_bits==15) + prec_bits-=LITTLENUM_NUMBER_OF_BITS+1; + + 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; + } + if(precision==X_PRECISION && exponent_bits==15) { + *lp++=0; + *lp++=0; + num_bits-=LITTLENUM_NUMBER_OF_BITS-1; + } + 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; + *lp++=0; + if(num_bits==LITTLENUM_NUMBER_OF_BITS) { + *lp++=0; + *lp++=next_bits(LITTLENUM_NUMBER_OF_BITS-1); + } else if(num_bits==LITTLENUM_NUMBER_OF_BITS-1) + *lp++=0; + else + *lp++=next_bits(LITTLENUM_NUMBER_OF_BITS-1-num_bits); + num_bits=0; + } else { + word1|= next_bits ((LITTLENUM_NUMBER_OF_BITS-1) - (exponent_bits+num_bits)); + *lp++=word1; + } + } + while(lp<words+precision) + *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 if((*lp&mask[prec_bits])!=mask[prec_bits]) + lp++; + } + + return return_value; + } else if (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: it has 16 bits of zero in the middle, + followed by a 1 bit. */ + if(exponent_bits==15 && precision==X_PRECISION) { + *lp++=0; + *lp++= 1<<(LITTLENUM_NUMBER_OF_BITS)|next_bits(LITTLENUM_NUMBER_OF_BITS-1); + } + + /* The rest of the words are just mantissa bits. */ + while(lp < words + precision) + *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 ( (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); +} + +/* 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) + */ +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?)"); +} + +#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); + bcopy(&arr[0],&dv,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); + bcopy(&arr[0],&fv,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 |
