aboutsummaryrefslogtreecommitdiff
path: root/fpu
diff options
context:
space:
mode:
authorJoseph Myers <joseph@codesourcery.com>2020-06-08 16:55:11 +0000
committerPaolo Bonzini <pbonzini@redhat.com>2020-06-26 09:39:37 -0400
commit6b8b0136ab3018e4b552b485f808bf66bcf19ead (patch)
tree40b45e6b43f886ef73ffd192e78392d67b6d42ac /fpu
parenteca30647fc078f4d9ed1b455bd67960f99dbeb7a (diff)
downloadqemu-6b8b0136ab3018e4b552b485f808bf66bcf19ead.zip
qemu-6b8b0136ab3018e4b552b485f808bf66bcf19ead.tar.gz
qemu-6b8b0136ab3018e4b552b485f808bf66bcf19ead.tar.bz2
softfloat: merge floatx80_mod and floatx80_rem
The m68k-specific softfloat code includes a function floatx80_mod that is extremely similar to floatx80_rem, but computing the remainder based on truncating the quotient toward zero rather than rounding it to nearest integer. This is also useful for emulating the x87 fprem and fprem1 instructions. Change the floatx80_rem implementation into floatx80_modrem that can perform either operation, with both floatx80_rem and floatx80_mod as thin wrappers available for all targets. There does not appear to be any use for the _mod operation for other floating-point formats in QEMU (the only other architectures using _rem at all are linux-user/arm/nwfpe, for FPA emulation, and openrisc, for instructions that have been removed in the latest version of the architecture), so no change is made to the code for other formats. Signed-off-by: Joseph Myers <joseph@codesourcery.com> Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Message-Id: <alpine.DEB.2.21.2006081654280.23637@digraph.polyomino.org.uk> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'fpu')
-rw-r--r--fpu/softfloat.c49
1 files changed, 38 insertions, 11 deletions
diff --git a/fpu/softfloat.c b/fpu/softfloat.c
index 5e9746c..b7dcf4d 100644
--- a/fpu/softfloat.c
+++ b/fpu/softfloat.c
@@ -5697,10 +5697,13 @@ floatx80 floatx80_div(floatx80 a, floatx80 b, float_status *status)
/*----------------------------------------------------------------------------
| Returns the remainder of the extended double-precision floating-point value
| `a' with respect to the corresponding value `b'. The operation is performed
-| according to the IEC/IEEE Standard for Binary Floating-Point Arithmetic.
+| according to the IEC/IEEE Standard for Binary Floating-Point Arithmetic,
+| if 'mod' is false; if 'mod' is true, return the remainder based on truncating
+| the quotient toward zero instead.
*----------------------------------------------------------------------------*/
-floatx80 floatx80_rem(floatx80 a, floatx80 b, float_status *status)
+floatx80 floatx80_modrem(floatx80 a, floatx80 b, bool mod,
+ float_status *status)
{
bool aSign, zSign;
int32_t aExp, bExp, expDiff;
@@ -5746,7 +5749,7 @@ floatx80 floatx80_rem(floatx80 a, floatx80 b, float_status *status)
expDiff = aExp - bExp;
aSig1 = 0;
if ( expDiff < 0 ) {
- if ( expDiff < -1 ) return a;
+ if ( mod || expDiff < -1 ) return a;
shift128Right( aSig0, 0, 1, &aSig0, &aSig1 );
expDiff = 0;
}
@@ -5778,14 +5781,16 @@ floatx80 floatx80_rem(floatx80 a, floatx80 b, float_status *status)
term1 = 0;
term0 = bSig;
}
- sub128( term0, term1, aSig0, aSig1, &alternateASig0, &alternateASig1 );
- if ( lt128( alternateASig0, alternateASig1, aSig0, aSig1 )
- || ( eq128( alternateASig0, alternateASig1, aSig0, aSig1 )
- && ( q & 1 ) )
- ) {
- aSig0 = alternateASig0;
- aSig1 = alternateASig1;
- zSign = ! zSign;
+ if (!mod) {
+ sub128( term0, term1, aSig0, aSig1, &alternateASig0, &alternateASig1 );
+ if ( lt128( alternateASig0, alternateASig1, aSig0, aSig1 )
+ || ( eq128( alternateASig0, alternateASig1, aSig0, aSig1 )
+ && ( q & 1 ) )
+ ) {
+ aSig0 = alternateASig0;
+ aSig1 = alternateASig1;
+ zSign = ! zSign;
+ }
}
return
normalizeRoundAndPackFloatx80(
@@ -5794,6 +5799,28 @@ floatx80 floatx80_rem(floatx80 a, floatx80 b, float_status *status)
}
/*----------------------------------------------------------------------------
+| Returns the remainder of the extended double-precision floating-point value
+| `a' with respect to the corresponding value `b'. The operation is performed
+| according to the IEC/IEEE Standard for Binary Floating-Point Arithmetic.
+*----------------------------------------------------------------------------*/
+
+floatx80 floatx80_rem(floatx80 a, floatx80 b, float_status *status)
+{
+ return floatx80_modrem(a, b, false, status);
+}
+
+/*----------------------------------------------------------------------------
+| Returns the remainder of the extended double-precision floating-point value
+| `a' with respect to the corresponding value `b', with the quotient truncated
+| toward zero.
+*----------------------------------------------------------------------------*/
+
+floatx80 floatx80_mod(floatx80 a, floatx80 b, float_status *status)
+{
+ return floatx80_modrem(a, b, true, status);
+}
+
+/*----------------------------------------------------------------------------
| Returns the square root of the extended double-precision floating-point
| value `a'. The operation is performed according to the IEC/IEEE Standard
| for Binary Floating-Point Arithmetic.