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freebsd/contrib/gcc/dfp.c
Alexander Kabaev 6b834ef156 GCC 4.2.0 release.
2007-05-19 01:19:51 +00:00

717 lines
17 KiB
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/* Decimal floating point support.
Copyright (C) 2005, 2006 Free Software Foundation, Inc.
This file is part of GCC.
GCC 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.
GCC 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 GCC; see the file COPYING. If not, write to the Free
Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301, USA. */
#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "tree.h"
#include "toplev.h"
#include "real.h"
#include "tm_p.h"
#include "dfp.h"
/* The order of the following headers is important for making sure
decNumber structure is large enough to hold decimal128 digits. */
#include "decimal128.h"
#include "decimal64.h"
#include "decimal32.h"
#include "decNumber.h"
static uint32_t
dfp_byte_swap (uint32_t in)
{
uint32_t out = 0;
unsigned char *p = (unsigned char *) &out;
union {
uint32_t i;
unsigned char b[4];
} u;
u.i = in;
p[0] = u.b[3];
p[1] = u.b[2];
p[2] = u.b[1];
p[3] = u.b[0];
return out;
}
/* Initialize R (a real with the decimal flag set) from DN. Can
utilize status passed in via CONTEXT, if a previous operation had
interesting status. */
static void
decimal_from_decnumber (REAL_VALUE_TYPE *r, decNumber *dn, decContext *context)
{
memset (r, 0, sizeof (REAL_VALUE_TYPE));
r->cl = rvc_normal;
if (decNumberIsZero (dn))
r->cl = rvc_zero;
if (decNumberIsNaN (dn))
r->cl = rvc_nan;
if (decNumberIsInfinite (dn))
r->cl = rvc_inf;
if (context->status & DEC_Overflow)
r->cl = rvc_inf;
if (decNumberIsNegative (dn))
r->sign = 1;
r->decimal = 1;
if (r->cl != rvc_normal)
return;
decContextDefault (context, DEC_INIT_DECIMAL128);
context->traps = 0;
decimal128FromNumber ((decimal128 *) r->sig, dn, context);
}
/* Create decimal encoded R from string S. */
void
decimal_real_from_string (REAL_VALUE_TYPE *r, const char *s)
{
decNumber dn;
decContext set;
decContextDefault (&set, DEC_INIT_DECIMAL128);
set.traps = 0;
decNumberFromString (&dn, (char *) s, &set);
/* It would be more efficient to store directly in decNumber format,
but that is impractical from current data structure size.
Encoding as a decimal128 is much more compact. */
decimal_from_decnumber (r, &dn, &set);
}
/* Initialize a decNumber from a REAL_VALUE_TYPE. */
static void
decimal_to_decnumber (const REAL_VALUE_TYPE *r, decNumber *dn)
{
decContext set;
decContextDefault (&set, DEC_INIT_DECIMAL128);
set.traps = 0;
switch (r->cl)
{
case rvc_zero:
decNumberZero (dn);
break;
case rvc_inf:
decNumberFromString (dn, (char *)"Infinity", &set);
break;
case rvc_nan:
if (r->signalling)
decNumberFromString (dn, (char *)"snan", &set);
else
decNumberFromString (dn, (char *)"nan", &set);
break;
case rvc_normal:
gcc_assert (r->decimal);
decimal128ToNumber ((decimal128 *) r->sig, dn);
break;
default:
gcc_unreachable ();
}
/* Fix up sign bit. */
if (r->sign != decNumberIsNegative (dn))
dn->bits ^= DECNEG;
}
/* Encode a real into an IEEE 754R decimal32 type. */
void
encode_decimal32 (const struct real_format *fmt ATTRIBUTE_UNUSED,
long *buf, const REAL_VALUE_TYPE *r)
{
decNumber dn;
decimal32 d32;
decContext set;
decContextDefault (&set, DEC_INIT_DECIMAL128);
set.traps = 0;
decimal_to_decnumber (r, &dn);
decimal32FromNumber (&d32, &dn, &set);
if (FLOAT_WORDS_BIG_ENDIAN)
buf[0] = *(uint32_t *) d32.bytes;
else
buf[0] = dfp_byte_swap (*(uint32_t *) d32.bytes);
}
/* Decode an IEEE 754R decimal32 type into a real. */
void
decode_decimal32 (const struct real_format *fmt ATTRIBUTE_UNUSED,
REAL_VALUE_TYPE *r, const long *buf)
{
decNumber dn;
decimal32 d32;
decContext set;
decContextDefault (&set, DEC_INIT_DECIMAL128);
set.traps = 0;
if (FLOAT_WORDS_BIG_ENDIAN)
*((uint32_t *) d32.bytes) = (uint32_t) buf[0];
else
*((uint32_t *) d32.bytes) = dfp_byte_swap ((uint32_t) buf[0]);
decimal32ToNumber (&d32, &dn);
decimal_from_decnumber (r, &dn, &set);
}
/* Encode a real into an IEEE 754R decimal64 type. */
void
encode_decimal64 (const struct real_format *fmt ATTRIBUTE_UNUSED,
long *buf, const REAL_VALUE_TYPE *r)
{
decNumber dn;
decimal64 d64;
decContext set;
decContextDefault (&set, DEC_INIT_DECIMAL128);
set.traps = 0;
decimal_to_decnumber (r, &dn);
decimal64FromNumber (&d64, &dn, &set);
if (FLOAT_WORDS_BIG_ENDIAN)
{
buf[0] = *(uint32_t *) &d64.bytes[0];
buf[1] = *(uint32_t *) &d64.bytes[4];
}
else
{
buf[1] = dfp_byte_swap (*(uint32_t *) &d64.bytes[0]);
buf[0] = dfp_byte_swap (*(uint32_t *) &d64.bytes[4]);
}
}
/* Decode an IEEE 754R decimal64 type into a real. */
void
decode_decimal64 (const struct real_format *fmt ATTRIBUTE_UNUSED,
REAL_VALUE_TYPE *r, const long *buf)
{
decNumber dn;
decimal64 d64;
decContext set;
decContextDefault (&set, DEC_INIT_DECIMAL128);
set.traps = 0;
if (FLOAT_WORDS_BIG_ENDIAN)
{
*((uint32_t *) &d64.bytes[0]) = (uint32_t) buf[0];
*((uint32_t *) &d64.bytes[4]) = (uint32_t) buf[1];
}
else
{
*((uint32_t *) &d64.bytes[0]) = dfp_byte_swap ((uint32_t) buf[1]);
*((uint32_t *) &d64.bytes[4]) = dfp_byte_swap ((uint32_t) buf[0]);
}
decimal64ToNumber (&d64, &dn);
decimal_from_decnumber (r, &dn, &set);
}
/* Encode a real into an IEEE 754R decimal128 type. */
void
encode_decimal128 (const struct real_format *fmt ATTRIBUTE_UNUSED,
long *buf, const REAL_VALUE_TYPE *r)
{
decNumber dn;
decContext set;
decimal128 d128;
decContextDefault (&set, DEC_INIT_DECIMAL128);
set.traps = 0;
decimal_to_decnumber (r, &dn);
decimal128FromNumber (&d128, &dn, &set);
if (FLOAT_WORDS_BIG_ENDIAN)
{
buf[0] = *(uint32_t *) &d128.bytes[0];
buf[1] = *(uint32_t *) &d128.bytes[4];
buf[2] = *(uint32_t *) &d128.bytes[8];
buf[3] = *(uint32_t *) &d128.bytes[12];
}
else
{
buf[0] = dfp_byte_swap (*(uint32_t *) &d128.bytes[12]);
buf[1] = dfp_byte_swap (*(uint32_t *) &d128.bytes[8]);
buf[2] = dfp_byte_swap (*(uint32_t *) &d128.bytes[4]);
buf[3] = dfp_byte_swap (*(uint32_t *) &d128.bytes[0]);
}
}
/* Decode an IEEE 754R decimal128 type into a real. */
void
decode_decimal128 (const struct real_format *fmt ATTRIBUTE_UNUSED,
REAL_VALUE_TYPE *r, const long *buf)
{
decNumber dn;
decimal128 d128;
decContext set;
decContextDefault (&set, DEC_INIT_DECIMAL128);
set.traps = 0;
if (FLOAT_WORDS_BIG_ENDIAN)
{
*((uint32_t *) &d128.bytes[0]) = (uint32_t) buf[0];
*((uint32_t *) &d128.bytes[4]) = (uint32_t) buf[1];
*((uint32_t *) &d128.bytes[8]) = (uint32_t) buf[2];
*((uint32_t *) &d128.bytes[12]) = (uint32_t) buf[3];
}
else
{
*((uint32_t *) &d128.bytes[0]) = dfp_byte_swap ((uint32_t) buf[3]);
*((uint32_t *) &d128.bytes[4]) = dfp_byte_swap ((uint32_t) buf[2]);
*((uint32_t *) &d128.bytes[8]) = dfp_byte_swap ((uint32_t) buf[1]);
*((uint32_t *) &d128.bytes[12]) = dfp_byte_swap ((uint32_t) buf[0]);
}
decimal128ToNumber (&d128, &dn);
decimal_from_decnumber (r, &dn, &set);
}
/* Helper function to convert from a binary real internal
representation. */
static void
decimal_to_binary (REAL_VALUE_TYPE *to, const REAL_VALUE_TYPE *from,
enum machine_mode mode)
{
char string[256];
decimal128 *d128;
d128 = (decimal128 *) from->sig;
decimal128ToString (d128, string);
real_from_string3 (to, string, mode);
}
/* Helper function to convert from a binary real internal
representation. */
static void
decimal_from_binary (REAL_VALUE_TYPE *to, const REAL_VALUE_TYPE *from)
{
char string[256];
/* We convert to string, then to decNumber then to decimal128. */
real_to_decimal (string, from, sizeof (string), 0, 1);
decimal_real_from_string (to, string);
}
/* Helper function to real.c:do_compare() to handle decimal internal
representation including when one of the operands is still in the
binary internal representation. */
int
decimal_do_compare (const REAL_VALUE_TYPE *a, const REAL_VALUE_TYPE *b,
int nan_result)
{
decContext set;
decNumber dn, dn2, dn3;
REAL_VALUE_TYPE a1, b1;
/* If either operand is non-decimal, create temporary versions. */
if (!a->decimal)
{
decimal_from_binary (&a1, a);
a = &a1;
}
if (!b->decimal)
{
decimal_from_binary (&b1, b);
b = &b1;
}
/* Convert into decNumber form for comparison operation. */
decContextDefault (&set, DEC_INIT_DECIMAL128);
set.traps = 0;
decimal128ToNumber ((decimal128 *) a->sig, &dn2);
decimal128ToNumber ((decimal128 *) b->sig, &dn3);
/* Finally, do the comparison. */
decNumberCompare (&dn, &dn2, &dn3, &set);
/* Return the comparison result. */
if (decNumberIsNaN (&dn))
return nan_result;
else if (decNumberIsZero (&dn))
return 0;
else if (decNumberIsNegative (&dn))
return -1;
else
return 1;
}
/* Helper to round_for_format, handling decimal float types. */
void
decimal_round_for_format (const struct real_format *fmt, REAL_VALUE_TYPE *r)
{
decNumber dn;
decContext set;
/* Real encoding occurs later. */
if (r->cl != rvc_normal)
return;
decContextDefault (&set, DEC_INIT_DECIMAL128);
set.traps = 0;
decimal128ToNumber ((decimal128 *) r->sig, &dn);
if (fmt == &decimal_quad_format)
{
/* The internal format is already in this format. */
return;
}
else if (fmt == &decimal_single_format)
{
decimal32 d32;
decContextDefault (&set, DEC_INIT_DECIMAL32);
set.traps = 0;
decimal32FromNumber (&d32, &dn, &set);
decimal32ToNumber (&d32, &dn);
}
else if (fmt == &decimal_double_format)
{
decimal64 d64;
decContextDefault (&set, DEC_INIT_DECIMAL64);
set.traps = 0;
decimal64FromNumber (&d64, &dn, &set);
decimal64ToNumber (&d64, &dn);
}
else
gcc_unreachable ();
decimal_from_decnumber (r, &dn, &set);
}
/* Extend or truncate to a new mode. Handles conversions between
binary and decimal types. */
void
decimal_real_convert (REAL_VALUE_TYPE *r, enum machine_mode mode,
const REAL_VALUE_TYPE *a)
{
const struct real_format *fmt = REAL_MODE_FORMAT (mode);
if (a->decimal && fmt->b == 10)
return;
if (a->decimal)
decimal_to_binary (r, a, mode);
else
decimal_from_binary (r, a);
}
/* Render R_ORIG as a decimal floating point constant. Emit DIGITS
significant digits in the result, bounded by BUF_SIZE. If DIGITS
is 0, choose the maximum for the representation. If
CROP_TRAILING_ZEROS, strip trailing zeros. Currently, not honoring
DIGITS or CROP_TRAILING_ZEROS. */
void
decimal_real_to_decimal (char *str, const REAL_VALUE_TYPE *r_orig,
size_t buf_size,
size_t digits ATTRIBUTE_UNUSED,
int crop_trailing_zeros ATTRIBUTE_UNUSED)
{
decimal128 *d128 = (decimal128*) r_orig->sig;
/* decimal128ToString requires space for at least 24 characters;
Require two more for suffix. */
gcc_assert (buf_size >= 24);
decimal128ToString (d128, str);
}
static bool
decimal_do_add (REAL_VALUE_TYPE *r, const REAL_VALUE_TYPE *op0,
const REAL_VALUE_TYPE *op1, int subtract_p)
{
decNumber dn;
decContext set;
decNumber dn2, dn3;
decimal_to_decnumber (op0, &dn2);
decimal_to_decnumber (op1, &dn3);
decContextDefault (&set, DEC_INIT_DECIMAL128);
set.traps = 0;
if (subtract_p)
decNumberSubtract (&dn, &dn2, &dn3, &set);
else
decNumberAdd (&dn, &dn2, &dn3, &set);
decimal_from_decnumber (r, &dn, &set);
/* Return true, if inexact. */
return (set.status & DEC_Inexact);
}
/* Compute R = OP0 * OP1. */
static bool
decimal_do_multiply (REAL_VALUE_TYPE *r, const REAL_VALUE_TYPE *op0,
const REAL_VALUE_TYPE *op1)
{
decContext set;
decNumber dn, dn2, dn3;
decimal_to_decnumber (op0, &dn2);
decimal_to_decnumber (op1, &dn3);
decContextDefault (&set, DEC_INIT_DECIMAL128);
set.traps = 0;
decNumberMultiply (&dn, &dn2, &dn3, &set);
decimal_from_decnumber (r, &dn, &set);
/* Return true, if inexact. */
return (set.status & DEC_Inexact);
}
/* Compute R = OP0 / OP1. */
static bool
decimal_do_divide (REAL_VALUE_TYPE *r, const REAL_VALUE_TYPE *op0,
const REAL_VALUE_TYPE *op1)
{
decContext set;
decNumber dn, dn2, dn3;
decimal_to_decnumber (op0, &dn2);
decimal_to_decnumber (op1, &dn3);
decContextDefault (&set, DEC_INIT_DECIMAL128);
set.traps = 0;
decNumberDivide (&dn, &dn2, &dn3, &set);
decimal_from_decnumber (r, &dn, &set);
/* Return true, if inexact. */
return (set.status & DEC_Inexact);
}
/* Set R to A truncated to an integral value toward zero (decimal
floating point). */
void
decimal_do_fix_trunc (REAL_VALUE_TYPE *r, const REAL_VALUE_TYPE *a)
{
decNumber dn, dn2;
decContext set;
decContextDefault (&set, DEC_INIT_DECIMAL128);
set.traps = 0;
set.round = DEC_ROUND_DOWN;
decimal128ToNumber ((decimal128 *) a->sig, &dn2);
decNumberToIntegralValue (&dn, &dn2, &set);
decimal_from_decnumber (r, &dn, &set);
}
/* Render decimal float value R as an integer. */
HOST_WIDE_INT
decimal_real_to_integer (const REAL_VALUE_TYPE *r)
{
decContext set;
decNumber dn, dn2, dn3;
REAL_VALUE_TYPE to;
char string[256];
decContextDefault (&set, DEC_INIT_DECIMAL128);
set.traps = 0;
set.round = DEC_ROUND_DOWN;
decimal128ToNumber ((decimal128 *) r->sig, &dn);
decNumberToIntegralValue (&dn2, &dn, &set);
decNumberZero (&dn3);
decNumberRescale (&dn, &dn2, &dn3, &set);
/* Convert to REAL_VALUE_TYPE and call appropriate conversion
function. */
decNumberToString (&dn, string);
real_from_string (&to, string);
return real_to_integer (&to);
}
/* Likewise, but to an integer pair, HI+LOW. */
void
decimal_real_to_integer2 (HOST_WIDE_INT *plow, HOST_WIDE_INT *phigh,
const REAL_VALUE_TYPE *r)
{
decContext set;
decNumber dn, dn2, dn3;
REAL_VALUE_TYPE to;
char string[256];
decContextDefault (&set, DEC_INIT_DECIMAL128);
set.traps = 0;
set.round = DEC_ROUND_DOWN;
decimal128ToNumber ((decimal128 *) r->sig, &dn);
decNumberToIntegralValue (&dn2, &dn, &set);
decNumberZero (&dn3);
decNumberRescale (&dn, &dn2, &dn3, &set);
/* Conver to REAL_VALUE_TYPE and call appropriate conversion
function. */
decNumberToString (&dn, string);
real_from_string (&to, string);
real_to_integer2 (plow, phigh, &to);
}
/* Perform the decimal floating point operation described by CODE.
For a unary operation, OP1 will be NULL. This function returns
true if the result may be inexact due to loss of precision. */
bool
decimal_real_arithmetic (REAL_VALUE_TYPE *r, enum tree_code code,
const REAL_VALUE_TYPE *op0,
const REAL_VALUE_TYPE *op1)
{
REAL_VALUE_TYPE a, b;
/* If either operand is non-decimal, create temporaries. */
if (!op0->decimal)
{
decimal_from_binary (&a, op0);
op0 = &a;
}
if (op1 && !op1->decimal)
{
decimal_from_binary (&b, op1);
op1 = &b;
}
switch (code)
{
case PLUS_EXPR:
return decimal_do_add (r, op0, op1, 0);
case MINUS_EXPR:
return decimal_do_add (r, op0, op1, 1);
case MULT_EXPR:
return decimal_do_multiply (r, op0, op1);
case RDIV_EXPR:
return decimal_do_divide (r, op0, op1);
case MIN_EXPR:
if (op1->cl == rvc_nan)
*r = *op1;
else if (real_compare (UNLT_EXPR, op0, op1))
*r = *op0;
else
*r = *op1;
return false;
case MAX_EXPR:
if (op1->cl == rvc_nan)
*r = *op1;
else if (real_compare (LT_EXPR, op0, op1))
*r = *op1;
else
*r = *op0;
return false;
case NEGATE_EXPR:
{
decimal128 *d128;
*r = *op0;
d128 = (decimal128 *) r->sig;
/* Flip high bit. */
d128->bytes[0] ^= 1 << 7;
/* Keep sign field in sync. */
r->sign ^= 1;
}
return false;
case ABS_EXPR:
{
decimal128 *d128;
*r = *op0;
d128 = (decimal128 *) r->sig;
/* Clear high bit. */
d128->bytes[0] &= 0x7f;
/* Keep sign field in sync. */
r->sign = 0;
}
return false;
case FIX_TRUNC_EXPR:
decimal_do_fix_trunc (r, op0);
return false;
default:
gcc_unreachable ();
}
}
/* Fills R with the largest finite value representable in mode MODE.
If SIGN is nonzero, R is set to the most negative finite value. */
void
decimal_real_maxval (REAL_VALUE_TYPE *r, int sign, enum machine_mode mode)
{
char *max;
switch (mode)
{
case SDmode:
max = (char *) "9.999999E96";
break;
case DDmode:
max = (char *) "9.999999999999999E384";
break;
case TDmode:
max = (char *) "9.999999999999999999999999999999999E6144";
break;
default:
gcc_unreachable ();
}
decimal_real_from_string (r, max);
if (sign)
r->sig[0] |= 0x80000000;
}
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