procyberian/gcc
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

real.c (encode_ieee_half): Define.

Browse source 
2009-05-15  Sandra Loosemore  <sandra@codesourcery.com>

	gcc/
	* real.c (encode_ieee_half): Define.
	(decode_ieee_half): Define.
	(ieee_half_format): Define.
	(arm_half_format): Define.
	* real.h (ieee_half_format): Declare.
	(arm_half_format): Declare.

From-SVN: r147579
This commit is contained in:
Sandra Loosemore 2009-05-15 10:22:58 -04:00 • committed by Sandra Loosemore
parent 1bd74ad980
commit ae63687c81
3 changed files with 172 additions and 0 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

9
gcc/ChangeLog
View file

@ -1,3 +1,12 @@
2009-05-15 Sandra Loosemore <sandra@codesourcery.com>
* real.c (encode_ieee_half): Define.
(decode_ieee_half): Define.
(ieee_half_format): Define.
(arm_half_format): Define.
* real.h (ieee_half_format): Declare.
(arm_half_format): Declare.
2009-05-15 Sandra Loosemore <sandra@codesourcery.com>
* optabs.c (prepare_float_lib_cmp): Test that the comparison,

161
gcc/real.c
View file

@ -4513,6 +4513,167 @@ const struct real_format decimal_quad_format =
false
};
/* Encode half-precision floats. This routine is used both for the IEEE
ARM alternative encodings. */
static void
encode_ieee_half (const struct real_format *fmt, long *buf,
const REAL_VALUE_TYPE *r)
{
unsigned long image, sig, exp;
unsigned long sign = r->sign;
bool denormal = (r->sig[SIGSZ-1] & SIG_MSB) == 0;
image = sign << 15;
sig = (r->sig[SIGSZ-1] >> (HOST_BITS_PER_LONG - 11)) & 0x3ff;
switch (r->cl)
{
case rvc_zero:
break;
case rvc_inf:
if (fmt->has_inf)
image |= 31 << 10;
else
image |= 0x7fff;
break;
case rvc_nan:
if (fmt->has_nans)
{
if (r->canonical)
sig = (fmt->canonical_nan_lsbs_set ? (1 << 9) - 1 : 0);
if (r->signalling == fmt->qnan_msb_set)
sig &= ~(1 << 9);
else
sig |= 1 << 9;
if (sig == 0)
sig = 1 << 8;
image |= 31 << 10;
image |= sig;
}
else
image |= 0x3ff;
break;
case rvc_normal:
/* Recall that IEEE numbers are interpreted as 1.F x 2**exp,
whereas the intermediate representation is 0.F x 2**exp.
Which means we're off by one. */
if (denormal)
exp = 0;
else
exp = REAL_EXP (r) + 15 - 1;
image |= exp << 10;
image |= sig;
break;
default:
gcc_unreachable ();
}
buf[0] = image;
}
/* Decode half-precision floats. This routine is used both for the IEEE
ARM alternative encodings. */
static void
decode_ieee_half (const struct real_format *fmt, REAL_VALUE_TYPE *r,
const long *buf)
{
unsigned long image = buf[0] & 0xffff;
bool sign = (image >> 15) & 1;
int exp = (image >> 10) & 0x1f;
memset (r, 0, sizeof (*r));
image <<= HOST_BITS_PER_LONG - 11;
image &= ~SIG_MSB;
if (exp == 0)
{
if (image && fmt->has_denorm)
{
r->cl = rvc_normal;
r->sign = sign;
SET_REAL_EXP (r, -14);
r->sig[SIGSZ-1] = image << 1;
normalize (r);
}
else if (fmt->has_signed_zero)
r->sign = sign;
}
else if (exp == 31 && (fmt->has_nans || fmt->has_inf))
{
if (image)
{
r->cl = rvc_nan;
r->sign = sign;
r->signalling = (((image >> (HOST_BITS_PER_LONG - 2)) & 1)
^ fmt->qnan_msb_set);
r->sig[SIGSZ-1] = image;
}
else
{
r->cl = rvc_inf;
r->sign = sign;
}
}
else
{
r->cl = rvc_normal;
r->sign = sign;
SET_REAL_EXP (r, exp - 15 + 1);
r->sig[SIGSZ-1] = image | SIG_MSB;
}
}
/* Half-precision format, as specified in IEEE 754R. */
const struct real_format ieee_half_format =
{
encode_ieee_half,
decode_ieee_half,
2,
11,
11,
-13,
16,
15,
15,
false,
true,
true,
true,
true,
true,
true,
false
};
/* ARM's alternative half-precision format, similar to IEEE but with
no reserved exponent value for NaNs and infinities; rather, it just
extends the range of exponents by one. */
const struct real_format arm_half_format =
{
encode_ieee_half,
decode_ieee_half,
2,
11,
11,
-13,
17,
15,
15,
false,
true,
false,
false,
true,
true,
false,
false
};
/* A synthetic "format" for internal arithmetic. It's the size of the
internal significand minus the two bits needed for proper rounding.
The encode and decode routines exist only to satisfy our paranoia

2
gcc/real.h
View file

@ -303,6 +303,8 @@ extern const struct real_format real_internal_format;
extern const struct real_format decimal_single_format;
extern const struct real_format decimal_double_format;
extern const struct real_format decimal_quad_format;
extern const struct real_format ieee_half_format;
extern const struct real_format arm_half_format;
/* ====================================================================== */