diff options
| -rw-r--r-- | fpu/softfloat.c | 79 | ||||
| -rw-r--r-- | fpu/softfloat.h | 3 |
2 files changed, 82 insertions, 0 deletions
diff --git a/fpu/softfloat.c b/fpu/softfloat.c index e6065b4bc7..0b8279798c 100644 --- a/fpu/softfloat.c +++ b/fpu/softfloat.c @@ -2056,6 +2056,85 @@ float32 float32_sqrt( float32 a STATUS_PARAM ) } /*---------------------------------------------------------------------------- +| Returns the binary exponential of the single-precision floating-point value +| `a'. The operation is performed according to the IEC/IEEE Standard for +| Binary Floating-Point Arithmetic. +| +| Uses the following identities: +| +| 1. ------------------------------------------------------------------------- +| x x*ln(2) +| 2 = e +| +| 2. ------------------------------------------------------------------------- +| 2 3 4 5 n +| x x x x x x x +| e = 1 + --- + --- + --- + --- + --- + ... + --- + ... +| 1! 2! 3! 4! 5! n! +*----------------------------------------------------------------------------*/ + +static const float64 float32_exp2_coefficients[15] = +{ + make_float64( 0x3ff0000000000000ll ), /* 1 */ + make_float64( 0x3fe0000000000000ll ), /* 2 */ + make_float64( 0x3fc5555555555555ll ), /* 3 */ + make_float64( 0x3fa5555555555555ll ), /* 4 */ + make_float64( 0x3f81111111111111ll ), /* 5 */ + make_float64( 0x3f56c16c16c16c17ll ), /* 6 */ + make_float64( 0x3f2a01a01a01a01all ), /* 7 */ + make_float64( 0x3efa01a01a01a01all ), /* 8 */ + make_float64( 0x3ec71de3a556c734ll ), /* 9 */ + make_float64( 0x3e927e4fb7789f5cll ), /* 10 */ + make_float64( 0x3e5ae64567f544e4ll ), /* 11 */ + make_float64( 0x3e21eed8eff8d898ll ), /* 12 */ + make_float64( 0x3de6124613a86d09ll ), /* 13 */ + make_float64( 0x3da93974a8c07c9dll ), /* 14 */ + make_float64( 0x3d6ae7f3e733b81fll ), /* 15 */ +}; + +float32 float32_exp2( float32 a STATUS_PARAM ) +{ + flag aSign; + int16 aExp; + bits32 aSig; + float64 r, x, xn; + int i; + + aSig = extractFloat32Frac( a ); + aExp = extractFloat32Exp( a ); + aSign = extractFloat32Sign( a ); + + if ( aExp == 0xFF) { + if ( aSig ) return propagateFloat32NaN( a, float32_zero STATUS_VAR ); + return (aSign) ? float32_zero : a; + } + if (aExp == 0) { + if (aSig == 0) return float32_one; + } + + float_raise( float_flag_inexact STATUS_VAR); + + /* ******************************* */ + /* using float64 for approximation */ + /* ******************************* */ + x = float32_to_float64(a STATUS_VAR); + x = float64_mul(x, float64_ln2 STATUS_VAR); + + xn = x; + r = float64_one; + for (i = 0 ; i < 15 ; i++) { + float64 f; + + f = float64_mul(xn, float32_exp2_coefficients[i] STATUS_VAR); + r = float64_add(r, f STATUS_VAR); + + xn = float64_mul(xn, x STATUS_VAR); + } + + return float64_to_float32(r, status); +} + +/*---------------------------------------------------------------------------- | Returns the binary log of the single-precision floating-point value `a'. | The operation is performed according to the IEC/IEEE Standard for Binary | Floating-Point Arithmetic. diff --git a/fpu/softfloat.h b/fpu/softfloat.h index 636591b04c..9528825522 100644 --- a/fpu/softfloat.h +++ b/fpu/softfloat.h @@ -275,6 +275,7 @@ float32 float32_mul( float32, float32 STATUS_PARAM ); float32 float32_div( float32, float32 STATUS_PARAM ); float32 float32_rem( float32, float32 STATUS_PARAM ); float32 float32_sqrt( float32 STATUS_PARAM ); +float32 float32_exp2( float32 STATUS_PARAM ); float32 float32_log2( float32 STATUS_PARAM ); int float32_eq( float32, float32 STATUS_PARAM ); int float32_le( float32, float32 STATUS_PARAM ); @@ -315,6 +316,7 @@ INLINE int float32_is_zero(float32 a) #define float32_zero make_float32(0) #define float32_one make_float32(0x3f800000) +#define float32_ln2 make_float32(0x3f317218) /*---------------------------------------------------------------------------- | Software IEC/IEEE double-precision conversion routines. @@ -386,6 +388,7 @@ INLINE int float64_is_zero(float64 a) #define float64_zero make_float64(0) #define float64_one make_float64(0x3ff0000000000000LL) +#define float64_ln2 make_float64(0x3fe62e42fefa39efLL) #ifdef FLOATX80 |