Commit 445810ec authored by Joseph Myers's avatar Joseph Myers Committed by Paolo Bonzini
Browse files

softfloat: return low bits of quotient from floatx80_modrem 



Both x87 and m68k need the low parts of the quotient for their
remainder operations.  Arrange for floatx80_modrem to track those bits
and return them via a pointer.

The architectures using float32_rem and float64_rem do not appear to
need this information, so the *_rem interface is left unchanged and
the information returned only from floatx80_modrem.  The logic used to
determine the low 7 bits of the quotient for m68k
(target/m68k/fpu_helper.c:make_quotient) appears completely bogus (it
looks at the result of converting the remainder to integer, the
quotient having been discarded by that point); this patch does not
change that, but the m68k maintainers may wish to do so.

Signed-off-by: default avatarJoseph Myers <joseph@codesourcery.com>
Reviewed-by: default avatarRichard Henderson <richard.henderson@linaro.org>
Message-Id: <alpine.DEB.2.21.2006081656500.23637@digraph.polyomino.org.uk>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 566601f1

fpu/softfloat.c

+18 −5
Original line number Diff line number Diff line
@@ -5699,10 +5699,11 @@ floatx80 floatx80_div(floatx80 a, floatx80 b, float_status *status) 
| `a' with respect to the corresponding value `b'.  The operation is performed

| 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.

| the quotient toward zero instead.  '*quotient' is set to the low 64 bits of

| the absolute value of the integer quotient.

*----------------------------------------------------------------------------*/



floatx80 floatx80_modrem(floatx80 a, floatx80 b, bool mod,

floatx80 floatx80_modrem(floatx80 a, floatx80 b, bool mod, uint64_t *quotient,

                         float_status *status)

{

    bool aSign, zSign;
@@ -5710,6 +5711,7 @@ floatx80 floatx80_modrem(floatx80 a, floatx80 b, bool mod, 
    uint64_t aSig0, aSig1, bSig;

    uint64_t q, term0, term1, alternateASig0, alternateASig1;



    *quotient = 0;

    if (floatx80_invalid_encoding(a) || floatx80_invalid_encoding(b)) {

        float_raise(float_flag_invalid, status);

        return floatx80_default_nan(status);
@@ -5768,7 +5770,7 @@ floatx80 floatx80_modrem(floatx80 a, floatx80 b, bool mod, 
        shift128Right( aSig0, 0, 1, &aSig0, &aSig1 );

        expDiff = 0;

    }

    q = ( bSig <= aSig0 );

    *quotient = q = ( bSig <= aSig0 );

    if ( q ) aSig0 -= bSig;

    expDiff -= 64;

    while ( 0 < expDiff ) {
@@ -5778,6 +5780,8 @@ floatx80 floatx80_modrem(floatx80 a, floatx80 b, bool mod, 
        sub128( aSig0, aSig1, term0, term1, &aSig0, &aSig1 );

        shortShift128Left( aSig0, aSig1, 62, &aSig0, &aSig1 );

        expDiff -= 62;

        *quotient <<= 62;

        *quotient += q;

    }

    expDiff += 64;

    if ( 0 < expDiff ) {
@@ -5791,6 +5795,12 @@ floatx80 floatx80_modrem(floatx80 a, floatx80 b, bool mod, 
            ++q;

            sub128( aSig0, aSig1, term0, term1, &aSig0, &aSig1 );

        }

        if (expDiff < 64) {

            *quotient <<= expDiff;

        } else {

            *quotient = 0;

        }

        *quotient += q;

    }

    else {

        term1 = 0;
@@ -5805,6 +5815,7 @@ floatx80 floatx80_modrem(floatx80 a, floatx80 b, bool mod, 
            aSig0 = alternateASig0;

            aSig1 = alternateASig1;

            zSign = ! zSign;

            ++*quotient;

        }

    }

    return
@@ -5821,7 +5832,8 @@ floatx80 floatx80_modrem(floatx80 a, floatx80 b, bool mod, 


floatx80 floatx80_rem(floatx80 a, floatx80 b, float_status *status)

{

    return floatx80_modrem(a, b, false, status);

    uint64_t quotient;

    return floatx80_modrem(a, b, false, &quotient, status);

}



/*----------------------------------------------------------------------------
@@ -5832,7 +5844,8 @@ floatx80 floatx80_rem(floatx80 a, floatx80 b, float_status *status) 


floatx80 floatx80_mod(floatx80 a, floatx80 b, float_status *status)

{

    return floatx80_modrem(a, b, true, status);

    uint64_t quotient;

    return floatx80_modrem(a, b, true, &quotient, status);

}



/*----------------------------------------------------------------------------

include/fpu/softfloat.h

+2 −1
Original line number Diff line number Diff line
@@ -687,7 +687,8 @@ floatx80 floatx80_add(floatx80, floatx80, float_status *status); 
floatx80 floatx80_sub(floatx80, floatx80, float_status *status);

floatx80 floatx80_mul(floatx80, floatx80, float_status *status);

floatx80 floatx80_div(floatx80, floatx80, float_status *status);

floatx80 floatx80_modrem(floatx80, floatx80, bool, float_status *status);

floatx80 floatx80_modrem(floatx80, floatx80, bool, uint64_t *,

                         float_status *status);

floatx80 floatx80_mod(floatx80, floatx80, float_status *status);

floatx80 floatx80_rem(floatx80, floatx80, float_status *status);

floatx80 floatx80_sqrt(floatx80, float_status *status);