diff options
Diffstat (limited to 'newlib/libm/mathfp/sf_pow.c')
| -rw-r--r-- | newlib/libm/mathfp/sf_pow.c | 65 |
1 files changed, 41 insertions, 24 deletions
diff --git a/newlib/libm/mathfp/sf_pow.c b/newlib/libm/mathfp/sf_pow.c index 2b3bed3c7..7f40186da 100644 --- a/newlib/libm/mathfp/sf_pow.c +++ b/newlib/libm/mathfp/sf_pow.c @@ -7,56 +7,66 @@ float powf (float x, float y) { float d, t, r = 1.0; - int n, k, sign = 0; + int n, k, sign = 0, exponent_is_even_int = 0; __int32_t px; GET_FLOAT_WORD (px, x); k = modff (y, &d); + if (k == 0.0) { + /* Exponent y is an integer. */ if (modff (ldexpf (y, -1), &t)) - sign = 0; + { + /* y is odd. */ + exponent_is_even_int = 0; + } else - sign = 1; + { + /* y is even. */ + exponent_is_even_int = 1; + } } - if (x == 0.0 && y <= 0.0) - errno = EDOM; - + if (x == 0.0 && y <= 0.0) + { + errno = EDOM; + } else if ((t = y * log (fabsf (x))) >= BIGX) { errno = ERANGE; if (px & 0x80000000) { - if (!k) + /* x is negative. */ + if (k) { + /* y is not an integer. */ errno = EDOM; x = 0.0; } - else if (sign) - x = -z_infinity_f.f; + else if (exponent_is_even_int) + x = z_infinity_f.f; else - x = z_infinity_f.f; + x = -z_infinity_f.f; } - - else - x = z_infinity_f.f; - } - + else + { + x = z_infinity_f.f; + } + } else if (t < SMALLX) { errno = ERANGE; x = 0.0; } - else { - if ( k && fabsf (d) <= 32767 ) + if ( !k && fabsf (d) <= 32767 ) { n = (int) d; - if (sign = (n < 0)) + if ((sign = (n < 0))) n = -n; while ( n > 0 ) @@ -72,13 +82,14 @@ float powf (float x, float y) return r; } - else { if ( px & 0x80000000 ) { - if ( !k ) + /* x is negative. */ + if (k) { + /* y is not an integer. */ errno = EDOM; return 0.0; } @@ -86,13 +97,19 @@ float powf (float x, float y) x = exp (t); - if ( sign ) + if (!exponent_is_even_int) { - px ^= 0x80000000; - SET_FLOAT_WORD (x, px); + if (px & 0x80000000) + { + /* y is an odd integer, and x is negative, + so the result is negative. */ + GET_FLOAT_WORD (px, x); + px |= 0x80000000; + SET_FLOAT_WORD (x, px); + } } } - } + } return x; } |