diff mbox series

[v2,12/20] fpu/softfloat: re-factor mul

Message ID 20180109122252.17670-13-alex.bennee@linaro.org
State Superseded
Headers show
Series re-factor softfloat and add fp16 functions | expand

Commit Message

Alex Bennée Jan. 9, 2018, 12:22 p.m. UTC 
We can now add float16_mul and use the common decompose and
canonicalize functions to have a single implementation for
float16/32/64 versions.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

---
 fpu/softfloat.c         | 207 ++++++++++++++++++------------------------------
 include/fpu/softfloat.h |   1 +
 2 files changed, 80 insertions(+), 128 deletions(-)

-- 
2.15.1

Comments

Philippe Mathieu-Daudé Jan. 9, 2018, 12:43 p.m. UTC | #1 
On 01/09/2018 09:22 AM, Alex Bennée wrote:
> We can now add float16_mul and use the common decompose and

> canonicalize functions to have a single implementation for

> float16/32/64 versions.

> 

> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>

> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>


better safe than sorry :P
Peter Maydell Jan. 12, 2018, 4:17 p.m. UTC | #2 
On 9 January 2018 at 12:22, Alex Bennée <alex.bennee@linaro.org> wrote:
> We can now add float16_mul and use the common decompose and

> canonicalize functions to have a single implementation for

> float16/32/64 versions.

>

> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>

> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

> ---

>  fpu/softfloat.c         | 207 ++++++++++++++++++------------------------------

>  include/fpu/softfloat.h |   1 +

>  2 files changed, 80 insertions(+), 128 deletions(-)

>

> diff --git a/fpu/softfloat.c b/fpu/softfloat.c

> index f89e47e3ef..6e9d4c172c 100644

> --- a/fpu/softfloat.c

> +++ b/fpu/softfloat.c

> @@ -730,6 +730,85 @@ float64 float64_sub(float64 a, float64 b, float_status *status)

>      return float64_round_pack_canonical(pr, status);

>  }

>

> +/*

> + * Returns the result of multiplying the floating-point values `a' and

> + * `b'. The operation is performed according to the IEC/IEEE Standard

> + * for Binary Floating-Point Arithmetic.

> + */

> +

> +static decomposed_parts mul_decomposed(decomposed_parts a, decomposed_parts b,

> +                                       float_status *s)

> +{

> +    bool sign = a.sign ^ b.sign;

> +

> +    if (a.cls == float_class_normal && b.cls == float_class_normal) {

> +        uint64_t hi, lo;

> +        int exp = a.exp + b.exp;

> +

> +        mul64To128(a.frac, b.frac, &hi, &lo);

> +        shift128RightJamming(hi, lo, DECOMPOSED_BINARY_POINT, &hi, &lo);

> +        if (lo & DECOMPOSED_OVERFLOW_BIT) {

> +            shift64RightJamming(lo, 1, &lo);

> +            exp += 1;

> +        }

> +

> +        /* Re-use a */

> +        a.exp = exp;

> +        a.sign = sign;

> +        a.frac = lo;

> +        return a;

> +    }

> +    /* handle all the NaN cases */

> +    if (a.cls >= float_class_qnan || b.cls >= float_class_qnan) {

> +        return pick_nan_parts(a, b, s);

> +    }

> +    /* Inf * Zero == NaN */

> +    if (((1 << a.cls) | (1 << b.cls)) ==

> +        ((1 << float_class_inf) | (1 << float_class_zero))) {


This is kinda confusing...

> +        s->float_exception_flags |= float_flag_invalid;

> +        a.cls = float_class_dnan;

> +        a.sign = sign;

> +        return a;

> +    }

> +    /* Multiply by 0 or Inf */

> +    if (a.cls == float_class_inf || a.cls == float_class_zero) {

> +        a.sign = sign;

> +        return a;

> +    }

> +    if (b.cls == float_class_inf || b.cls == float_class_zero) {

> +        b.sign = sign;

> +        return b;

> +    }

> +    g_assert_not_reached();

> +}


thanks
-- PMM
Alex Bennée Jan. 16, 2018, 10:16 a.m. UTC | #3 
Peter Maydell <peter.maydell@linaro.org> writes:

> On 9 January 2018 at 12:22, Alex Bennée <alex.bennee@linaro.org> wrote:

>> We can now add float16_mul and use the common decompose and

>> canonicalize functions to have a single implementation for

>> float16/32/64 versions.

>>

>> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>

>> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

>> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

>> ---

>>  fpu/softfloat.c         | 207 ++++++++++++++++++------------------------------

>>  include/fpu/softfloat.h |   1 +

>>  2 files changed, 80 insertions(+), 128 deletions(-)

>>

>> diff --git a/fpu/softfloat.c b/fpu/softfloat.c

>> index f89e47e3ef..6e9d4c172c 100644

>> --- a/fpu/softfloat.c

>> +++ b/fpu/softfloat.c

>> @@ -730,6 +730,85 @@ float64 float64_sub(float64 a, float64 b, float_status *status)

>>      return float64_round_pack_canonical(pr, status);

>>  }

>>

>> +/*

>> + * Returns the result of multiplying the floating-point values `a' and

>> + * `b'. The operation is performed according to the IEC/IEEE Standard

>> + * for Binary Floating-Point Arithmetic.

>> + */

>> +

>> +static decomposed_parts mul_decomposed(decomposed_parts a, decomposed_parts b,

>> +                                       float_status *s)

>> +{

>> +    bool sign = a.sign ^ b.sign;

>> +

>> +    if (a.cls == float_class_normal && b.cls == float_class_normal) {

>> +        uint64_t hi, lo;

>> +        int exp = a.exp + b.exp;

>> +

>> +        mul64To128(a.frac, b.frac, &hi, &lo);

>> +        shift128RightJamming(hi, lo, DECOMPOSED_BINARY_POINT, &hi, &lo);

>> +        if (lo & DECOMPOSED_OVERFLOW_BIT) {

>> +            shift64RightJamming(lo, 1, &lo);

>> +            exp += 1;

>> +        }

>> +

>> +        /* Re-use a */

>> +        a.exp = exp;

>> +        a.sign = sign;

>> +        a.frac = lo;

>> +        return a;

>> +    }

>> +    /* handle all the NaN cases */

>> +    if (a.cls >= float_class_qnan || b.cls >= float_class_qnan) {

>> +        return pick_nan_parts(a, b, s);

>> +    }

>> +    /* Inf * Zero == NaN */

>> +    if (((1 << a.cls) | (1 << b.cls)) ==

>> +        ((1 << float_class_inf) | (1 << float_class_zero))) {

>

> This is kinda confusing...


Yeah it's a bit of a shortcut to:

  if ((a.cls == float_class_inf && b.cls == float_class_zero)
     ||
      (a.cls == float_class_zero && b.cls == float_class_inf))

Would you prefer it long hand or tidied away to a helper?

  if (cls_combination(a, b, float_class_inf, float_class_zero))

?

>

>> +        s->float_exception_flags |= float_flag_invalid;

>> +        a.cls = float_class_dnan;

>> +        a.sign = sign;

>> +        return a;

>> +    }

>> +    /* Multiply by 0 or Inf */

>> +    if (a.cls == float_class_inf || a.cls == float_class_zero) {

>> +        a.sign = sign;

>> +        return a;

>> +    }

>> +    if (b.cls == float_class_inf || b.cls == float_class_zero) {

>> +        b.sign = sign;

>> +        return b;

>> +    }

>> +    g_assert_not_reached();

>> +}

>

> thanks

> -- PMM



--
Alex Bennée
diff mbox series

Patch

diff --git a/fpu/softfloat.c b/fpu/softfloat.c
index f89e47e3ef..6e9d4c172c 100644
--- a/fpu/softfloat.c
+++ b/fpu/softfloat.c
@@ -730,6 +730,85 @@  float64 float64_sub(float64 a, float64 b, float_status *status)
     return float64_round_pack_canonical(pr, status);
 }
 
+/*
+ * Returns the result of multiplying the floating-point values `a' and
+ * `b'. The operation is performed according to the IEC/IEEE Standard
+ * for Binary Floating-Point Arithmetic.
+ */
+
+static decomposed_parts mul_decomposed(decomposed_parts a, decomposed_parts b,
+                                       float_status *s)
+{
+    bool sign = a.sign ^ b.sign;
+
+    if (a.cls == float_class_normal && b.cls == float_class_normal) {
+        uint64_t hi, lo;
+        int exp = a.exp + b.exp;
+
+        mul64To128(a.frac, b.frac, &hi, &lo);
+        shift128RightJamming(hi, lo, DECOMPOSED_BINARY_POINT, &hi, &lo);
+        if (lo & DECOMPOSED_OVERFLOW_BIT) {
+            shift64RightJamming(lo, 1, &lo);
+            exp += 1;
+        }
+
+        /* Re-use a */
+        a.exp = exp;
+        a.sign = sign;
+        a.frac = lo;
+        return a;
+    }
+    /* handle all the NaN cases */
+    if (a.cls >= float_class_qnan || b.cls >= float_class_qnan) {
+        return pick_nan_parts(a, b, s);
+    }
+    /* Inf * Zero == NaN */
+    if (((1 << a.cls) | (1 << b.cls)) ==
+        ((1 << float_class_inf) | (1 << float_class_zero))) {
+        s->float_exception_flags |= float_flag_invalid;
+        a.cls = float_class_dnan;
+        a.sign = sign;
+        return a;
+    }
+    /* Multiply by 0 or Inf */
+    if (a.cls == float_class_inf || a.cls == float_class_zero) {
+        a.sign = sign;
+        return a;
+    }
+    if (b.cls == float_class_inf || b.cls == float_class_zero) {
+        b.sign = sign;
+        return b;
+    }
+    g_assert_not_reached();
+}
+
+float16 float16_mul(float16 a, float16 b, float_status *status)
+{
+    decomposed_parts pa = float16_unpack_canonical(a, status);
+    decomposed_parts pb = float16_unpack_canonical(b, status);
+    decomposed_parts pr = mul_decomposed(pa, pb, status);
+
+    return float16_round_pack_canonical(pr, status);
+}
+
+float32 float32_mul(float32 a, float32 b, float_status *status)
+{
+    decomposed_parts pa = float32_unpack_canonical(a, status);
+    decomposed_parts pb = float32_unpack_canonical(b, status);
+    decomposed_parts pr = mul_decomposed(pa, pb, status);
+
+    return float32_round_pack_canonical(pr, status);
+}
+
+float64 float64_mul(float64 a, float64 b, float_status *status)
+{
+    decomposed_parts pa = float64_unpack_canonical(a, status);
+    decomposed_parts pb = float64_unpack_canonical(b, status);
+    decomposed_parts pr = mul_decomposed(pa, pb, 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
@@ -2542,70 +2621,6 @@  float32 float32_round_to_int(float32 a, float_status *status)
 }
 
 
-/*----------------------------------------------------------------------------
-| Returns the result of multiplying the single-precision floating-point values
-| `a' and `b'.  The operation is performed according to the IEC/IEEE Standard
-| for Binary Floating-Point Arithmetic.
-*----------------------------------------------------------------------------*/
-
-float32 float32_mul(float32 a, float32 b, float_status *status)
-{
-    flag aSign, bSign, zSign;
-    int aExp, bExp, zExp;
-    uint32_t aSig, bSig;
-    uint64_t zSig64;
-    uint32_t zSig;
-
-    a = float32_squash_input_denormal(a, status);
-    b = float32_squash_input_denormal(b, status);
-
-    aSig = extractFloat32Frac( a );
-    aExp = extractFloat32Exp( a );
-    aSign = extractFloat32Sign( a );
-    bSig = extractFloat32Frac( b );
-    bExp = extractFloat32Exp( b );
-    bSign = extractFloat32Sign( b );
-    zSign = aSign ^ bSign;
-    if ( aExp == 0xFF ) {
-        if ( aSig || ( ( bExp == 0xFF ) && bSig ) ) {
-            return propagateFloat32NaN(a, b, status);
-        }
-        if ( ( bExp | bSig ) == 0 ) {
-            float_raise(float_flag_invalid, status);
-            return float32_default_nan(status);
-        }
-        return packFloat32( zSign, 0xFF, 0 );
-    }
-    if ( bExp == 0xFF ) {
-        if (bSig) {
-            return propagateFloat32NaN(a, b, status);
-        }
-        if ( ( aExp | aSig ) == 0 ) {
-            float_raise(float_flag_invalid, status);
-            return float32_default_nan(status);
-        }
-        return packFloat32( zSign, 0xFF, 0 );
-    }
-    if ( aExp == 0 ) {
-        if ( aSig == 0 ) return packFloat32( zSign, 0, 0 );
-        normalizeFloat32Subnormal( aSig, &aExp, &aSig );
-    }
-    if ( bExp == 0 ) {
-        if ( bSig == 0 ) return packFloat32( zSign, 0, 0 );
-        normalizeFloat32Subnormal( bSig, &bExp, &bSig );
-    }
-    zExp = aExp + bExp - 0x7F;
-    aSig = ( aSig | 0x00800000 )<<7;
-    bSig = ( bSig | 0x00800000 )<<8;
-    shift64RightJamming( ( (uint64_t) aSig ) * bSig, 32, &zSig64 );
-    zSig = zSig64;
-    if ( 0 <= (int32_t) ( zSig<<1 ) ) {
-        zSig <<= 1;
-        --zExp;
-    }
-    return roundAndPackFloat32(zSign, zExp, zSig, status);
-
-}
 
 /*----------------------------------------------------------------------------
 | Returns the result of dividing the single-precision floating-point value `a'
@@ -4138,70 +4153,6 @@  float64 float64_trunc_to_int(float64 a, float_status *status)
     return res;
 }
 
-
-/*----------------------------------------------------------------------------
-| Returns the result of multiplying the double-precision floating-point values
-| `a' and `b'.  The operation is performed according to the IEC/IEEE Standard
-| for Binary Floating-Point Arithmetic.
-*----------------------------------------------------------------------------*/
-
-float64 float64_mul(float64 a, float64 b, float_status *status)
-{
-    flag aSign, bSign, zSign;
-    int aExp, bExp, zExp;
-    uint64_t aSig, bSig, zSig0, zSig1;
-
-    a = float64_squash_input_denormal(a, status);
-    b = float64_squash_input_denormal(b, status);
-
-    aSig = extractFloat64Frac( a );
-    aExp = extractFloat64Exp( a );
-    aSign = extractFloat64Sign( a );
-    bSig = extractFloat64Frac( b );
-    bExp = extractFloat64Exp( b );
-    bSign = extractFloat64Sign( b );
-    zSign = aSign ^ bSign;
-    if ( aExp == 0x7FF ) {
-        if ( aSig || ( ( bExp == 0x7FF ) && bSig ) ) {
-            return propagateFloat64NaN(a, b, status);
-        }
-        if ( ( bExp | bSig ) == 0 ) {
-            float_raise(float_flag_invalid, status);
-            return float64_default_nan(status);
-        }
-        return packFloat64( zSign, 0x7FF, 0 );
-    }
-    if ( bExp == 0x7FF ) {
-        if (bSig) {
-            return propagateFloat64NaN(a, b, status);
-        }
-        if ( ( aExp | aSig ) == 0 ) {
-            float_raise(float_flag_invalid, status);
-            return float64_default_nan(status);
-        }
-        return packFloat64( zSign, 0x7FF, 0 );
-    }
-    if ( aExp == 0 ) {
-        if ( aSig == 0 ) return packFloat64( zSign, 0, 0 );
-        normalizeFloat64Subnormal( aSig, &aExp, &aSig );
-    }
-    if ( bExp == 0 ) {
-        if ( bSig == 0 ) return packFloat64( zSign, 0, 0 );
-        normalizeFloat64Subnormal( bSig, &bExp, &bSig );
-    }
-    zExp = aExp + bExp - 0x3FF;
-    aSig = ( aSig | LIT64( 0x0010000000000000 ) )<<10;
-    bSig = ( bSig | LIT64( 0x0010000000000000 ) )<<11;
-    mul64To128( aSig, bSig, &zSig0, &zSig1 );
-    zSig0 |= ( zSig1 != 0 );
-    if ( 0 <= (int64_t) ( zSig0<<1 ) ) {
-        zSig0 <<= 1;
-        --zExp;
-    }
-    return roundAndPackFloat64(zSign, zExp, zSig0, status);
-
-}
-
 /*----------------------------------------------------------------------------
 | Returns the result of dividing the double-precision floating-point value `a'
 | by the corresponding value `b'.  The operation is performed according to
diff --git a/include/fpu/softfloat.h b/include/fpu/softfloat.h
index 3a21a2bcef..cfee28061e 100644
--- a/include/fpu/softfloat.h
+++ b/include/fpu/softfloat.h
@@ -321,6 +321,7 @@  float64 float16_to_float64(float16 a, flag ieee, float_status *status);
 
 float16 float16_add(float16, float16, float_status *status);
 float16 float16_sub(float16, float16, float_status *status);
+float16 float16_mul(float16, float16, float_status *status);
 
 int float16_is_quiet_nan(float16, float_status *status);
 int float16_is_signaling_nan(float16, float_status *status);