Commit 0bfc9f19 authored by Alex Bennée's avatar Alex Bennée
Browse files

fpu/softfloat: re-factor scalbn 



This is one of the simpler manipulations you could make to a floating
point number.

Signed-off-by: default avatarAlex Bennée <alex.bennee@linaro.org>
Reviewed-by: default avatarRichard Henderson <richard.henderson@linaro.org>
parent c02e1fb8

fpu/softfloat.c

+33 −73
Original line number Diff line number Diff line
@@ -1663,6 +1663,39 @@ float64 uint16_to_float64(uint16_t a, float_status *status) 
    return uint64_to_float64(a, status);

}



/* Multiply A by 2 raised to the power N.  */

static FloatParts scalbn_decomposed(FloatParts a, int n, float_status *s)

{

    if (unlikely(is_nan(a.cls))) {

        return return_nan(a, s);

    }

    if (a.cls == float_class_normal) {

        a.exp += n;

    }

    return a;

}



float16 float16_scalbn(float16 a, int n, float_status *status)

{

    FloatParts pa = float16_unpack_canonical(a, status);

    FloatParts pr = scalbn_decomposed(pa, n, status);

    return float16_round_pack_canonical(pr, status);

}



float32 float32_scalbn(float32 a, int n, float_status *status)

{

    FloatParts pa = float32_unpack_canonical(a, status);

    FloatParts pr = scalbn_decomposed(pa, n, status);

    return float32_round_pack_canonical(pr, status);

}



float64 float64_scalbn(float64 a, int n, float_status *status)

{

    FloatParts pa = float64_unpack_canonical(a, status);

    FloatParts pr = scalbn_decomposed(pa, n, status);

    return float64_round_pack_canonical(pr, status);

}



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

| Takes a 64-bit fixed-point value `absZ' with binary point between bits 6

| and 7, and returns the properly rounded 32-bit integer corresponding to the
@@ -6986,79 +7019,6 @@ MINMAX(32) 
MINMAX(64)





/* Multiply A by 2 raised to the power N.  */

float32 float32_scalbn(float32 a, int n, float_status *status)

{

    flag aSign;

    int16_t aExp;

    uint32_t aSig;



    a = float32_squash_input_denormal(a, status);

    aSig = extractFloat32Frac( a );

    aExp = extractFloat32Exp( a );

    aSign = extractFloat32Sign( a );



    if ( aExp == 0xFF ) {

        if ( aSig ) {

            return propagateFloat32NaN(a, a, status);

        }

        return a;

    }

    if (aExp != 0) {

        aSig |= 0x00800000;

    } else if (aSig == 0) {

        return a;

    } else {

        aExp++;

    }



    if (n > 0x200) {

        n = 0x200;

    } else if (n < -0x200) {

        n = -0x200;

    }



    aExp += n - 1;

    aSig <<= 7;

    return normalizeRoundAndPackFloat32(aSign, aExp, aSig, status);

}



float64 float64_scalbn(float64 a, int n, float_status *status)

{

    flag aSign;

    int16_t aExp;

    uint64_t aSig;



    a = float64_squash_input_denormal(a, status);

    aSig = extractFloat64Frac( a );

    aExp = extractFloat64Exp( a );

    aSign = extractFloat64Sign( a );



    if ( aExp == 0x7FF ) {

        if ( aSig ) {

            return propagateFloat64NaN(a, a, status);

        }

        return a;

    }

    if (aExp != 0) {

        aSig |= LIT64( 0x0010000000000000 );

    } else if (aSig == 0) {

        return a;

    } else {

        aExp++;

    }



    if (n > 0x1000) {

        n = 0x1000;

    } else if (n < -0x1000) {

        n = -0x1000;

    }



    aExp += n - 1;

    aSig <<= 10;

    return normalizeRoundAndPackFloat64(aSign, aExp, aSig, status);

}



floatx80 floatx80_scalbn(floatx80 a, int n, float_status *status)

{

    flag aSign;

include/fpu/softfloat.h

+1 −0
Original line number Diff line number Diff line
@@ -244,6 +244,7 @@ float16 float16_sub(float16, float16, float_status *status); 
float16 float16_mul(float16, float16, float_status *status);

float16 float16_muladd(float16, float16, float16, int, float_status *status);

float16 float16_div(float16, float16, float_status *status);

float16 float16_scalbn(float16, int, float_status *status);



int float16_is_quiet_nan(float16, float_status *status);

int float16_is_signaling_nan(float16, float_status *status);