From: Ken Raeburn Date: Thu, 3 Dec 1992 23:42:16 +0000 (+0000) Subject: more tahoe code X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=88db8f81f252a5be9353e3c6f40c50c8622d1a2a;p=deliverable%2Fbinutils-gdb.git more tahoe code --- diff --git a/gas/config/atof-tahoe.c b/gas/config/atof-tahoe.c new file mode 100644 index 0000000000..a80c89ebfa --- /dev/null +++ b/gas/config/atof-tahoe.c @@ -0,0 +1,431 @@ + +/* atof_tahoe.c - turn a string into a Tahoe floating point number + Copyright (C) 1987 Free Software Foundation, Inc. + */ + +/* This is really a simplified version of atof_vax.c. I glommed it wholesale + and then shaved it down. I don't even know how it works. (Don't you find + my honesty refreshing? bowen@cs.Buffalo.EDU (Devon E Bowen) + + I don't allow uppercase letters in the precision descrpitors. Ie 'f' and + 'd' are allowed but 'F' and 'D' aren't */ + +#include "as.h" + +/* Precision in LittleNums. */ +#define MAX_PRECISION (4) +#define D_PRECISION (4) +#define F_PRECISION (2) + +/* Precision in chars. */ +#define D_PRECISION_CHARS (8) +#define F_PRECISION_CHARS (4) + +/* Length in LittleNums of guard bits. */ +#define GUARD (2) + +static const long int 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 +}; + + +/* Shared between flonum_gen2tahoe and next_bits */ +static int bits_left_in_littlenum; +static LITTLENUM_TYPE *littlenum_pointer; +static LITTLENUM_TYPE *littlenum_end; + +#if __STDC__ == 1 + +int flonum_gen2tahoe (int format_letter, FLONUM_TYPE * f, LITTLENUM_TYPE * words); + +#else /* not __STDC__ */ + +int flonum_gen2tahoe (); + +#endif /* not __STDC__ */ + + +static int +next_bits (number_of_bits) + int number_of_bits; +{ + int return_value; + + if (littlenum_pointer < littlenum_end) + 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; + bits_left_in_littlenum = LITTLENUM_NUMBER_OF_BITS - number_of_bits; + littlenum_pointer--; + if (littlenum_pointer >= littlenum_end) + 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); +} + +static void +make_invalid_floating_point_number (words) + LITTLENUM_TYPE *words; +{ + *words = 0x8000; /* Floating Reserved Operand Code */ +} + +static int /* 0 means letter is OK. */ +what_kind_of_float (letter, precisionP, exponent_bitsP) + char letter; /* In: lowercase please. What kind of float? */ + int *precisionP; /* Number of 16-bit words in the float. */ + long int *exponent_bitsP; /* Number of exponent bits. */ +{ + int retval; /* 0: OK. */ + + retval = 0; + switch (letter) + { + case 'f': + *precisionP = F_PRECISION; + *exponent_bitsP = 8; + break; + + case 'd': + *precisionP = D_PRECISION; + *exponent_bitsP = 8; + break; + + default: + retval = 69; + break; + } + return (retval); +} + +/***********************************************************************\ +* * +* Warning: this returns 16-bit LITTLENUMs, because that is * +* what the VAX thinks in. 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! * +* * +\***********************************************************************/ + +char * /* Return pointer past text consumed. */ +atof_tahoe (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. */ +{ + FLONUM_TYPE f; + 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 int exponent_bits; + + return_value = str; + f.low = bits + MAX_PRECISION; + f.high = NULL; + f.leader = NULL; + f.exponent = NULL; + f.sign = '\0'; + + if (what_kind_of_float (what_kind, &precision, &exponent_bits)) + { + return_value = NULL; /* We lost. */ + make_invalid_floating_point_number (words); + } + if (return_value) + { + memset (bits, '\0', sizeof (LITTLENUM_TYPE) * MAX_PRECISION); + + /* Use more LittleNums than seems */ + /* necessary: the highest flonum may have */ + /* 15 leading 0 bits, so could be useless. */ + f.high = f.low + precision - 1 + GUARD; + + if (atof_generic (&return_value, ".", "eE", &f)) + { + make_invalid_floating_point_number (words); + return_value = NULL; /* we lost */ + } + else + { + if (flonum_gen2tahoe (what_kind, &f, words)) + { + return_value = NULL; + } + } + } + return (return_value); +} + +/* + * In: a flonum, a Tahoe floating point format. + * Out: a Tahoe floating-point bit pattern. + */ + +int /* 0: OK. */ +flonum_gen2tahoe (format_letter, f, words) + char format_letter; /* One of 'd' 'f'. */ + FLONUM_TYPE *f; + LITTLENUM_TYPE *words; /* Deliver answer here. */ +{ + LITTLENUM_TYPE *lp; + int precision; + long int exponent_bits; + int return_value; /* 0 == OK. */ + + return_value = what_kind_of_float (format_letter, &precision, &exponent_bits); + if (return_value != 0) + { + make_invalid_floating_point_number (words); + } + else + { + if (f->low > f->leader) + { + /* 0.0e0 seen. */ + memset (words, '\0', sizeof (LITTLENUM_TYPE) * precision); + } + else + { + long int exponent_1; + long int exponent_2; + long int exponent_3; + long int exponent_4; + int exponent_skippage; + LITTLENUM_TYPE word1; + + /* JF: Deal with new Nan, +Inf and -Inf codes */ + if (f->sign != '-' && f->sign != '+') + { + make_invalid_floating_point_number (words); + return return_value; + } + /* + * All tahoe floating_point formats 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 are the next most significant bits. + * And so on for each other word. + * + * So we need: number of bits of exponent, number of bits of + * mantissa. + */ + + bits_left_in_littlenum = LITTLENUM_NUMBER_OF_BITS; + littlenum_pointer = f->leader; + littlenum_end = f->low; + /* Seek (and forget) 1st significant bit */ + for (exponent_skippage = 0; + !next_bits (1); + exponent_skippage++) + { + } + exponent_1 = f->exponent + f->leader + 1 - f->low; + /* Radix LITTLENUM_RADIX, point just higher than f -> 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)); + /* Offset exponent. */ + + if (exponent_4 & ~mask[exponent_bits]) + { + /* + * Exponent overflow. Lose immediately. + */ + + make_invalid_floating_point_number (words); + + /* + * We leave return_value alone: admit we read the + * number, but return a floating exception + * because we can't encode the number. + */ + } + else + { + lp = words; + + /* Word 1. Sign, exponent and perhaps high bits. */ + /* Assume 2's complement integers. */ + word1 = ((exponent_4 & mask[exponent_bits]) << (15 - exponent_bits)) + | ((f->sign == '+') ? 0 : 0x8000) + | next_bits (15 - exponent_bits); + *lp++ = word1; + + /* The rest of the words are just mantissa bits. */ + for (; lp < words + precision; lp++) + { + *lp = next_bits (LITTLENUM_NUMBER_OF_BITS); + } + + if (next_bits (1)) + { + /* + * 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? + */ + + unsigned long int carry; + + /* + #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))) + { + make_invalid_floating_point_number (words); + /* + * We leave return_value alone: admit we read the + * number, but return a floating exception + * because we can't encode the number. + */ + } + } /* if (we needed to round up) */ + } /* if (exponent overflow) */ + } /* if (0.0e0) */ + } /* if (float_type was OK) */ + return (return_value); +} + +/* + * md_atof() + * + * In: input_line_pointer -> the 1st character of a floating-point + * number. + * 1 letter denoting the type of statement that wants a + * binary floating point number returned. + * Address of where to build floating point literal. + * Assumed to be 'big enough'. + * Address of where to return size of literal (in chars). + * + * Out: Input_line_pointer -> of next char after floating number. + * Error message, or "". + * Floating point literal. + * Number of chars we used for the literal. + */ + +char * +md_atof (what_statement_type, literalP, sizeP) + char what_statement_type; + char *literalP; + int *sizeP; +{ + LITTLENUM_TYPE words[MAX_PRECISION]; + register char kind_of_float; + register int number_of_chars; + register LITTLENUM_TYPE *littlenum_pointer; + + switch (what_statement_type) + { + case 'f': /* .ffloat */ + case 'd': /* .dfloat */ + kind_of_float = what_statement_type; + break; + + default: + kind_of_float = 0; + break; + }; + + if (kind_of_float) + { + register LITTLENUM_TYPE *limit; + + input_line_pointer = atof_tahoe (input_line_pointer, + kind_of_float, + words); + /* + * The atof_tahoe() builds up 16-bit numbers. + * Since the assembler may not be running on + * a different-endian machine, be very careful about + * converting words to chars. + */ + number_of_chars = (kind_of_float == 'f' ? F_PRECISION_CHARS : + (kind_of_float == 'd' ? D_PRECISION_CHARS : 0)); + know (number_of_chars <= MAX_PRECISION * sizeof (LITTLENUM_TYPE)); + limit = words + (number_of_chars / sizeof (LITTLENUM_TYPE)); + for (littlenum_pointer = words; + littlenum_pointer < limit; + littlenum_pointer++) + { + md_number_to_chars (literalP, *littlenum_pointer, + sizeof (LITTLENUM_TYPE)); + literalP += sizeof (LITTLENUM_TYPE); + }; + } + else + { + number_of_chars = 0; + }; + + *sizeP = number_of_chars; + return (kind_of_float ? "" : "Bad call to md_atof()"); +} /* md_atof() */ + +/* atof_tahoe.c */