diff options
| -rw-r--r-- | libm/s_ilogb.c | 47 | ||||
| -rw-r--r-- | test/math/Makefile.in | 3 | ||||
| -rw-r--r-- | test/math/ilogb.c | 51 |
3 files changed, 84 insertions, 17 deletions
diff --git a/libm/s_ilogb.c b/libm/s_ilogb.c index ce3029667..259ae7b55 100644 --- a/libm/s_ilogb.c +++ b/libm/s_ilogb.c @@ -10,9 +10,10 @@ */ /* ilogb(double x) - * return the binary exponent of non-zero x - * ilogb(0) = 0x80000001 - * ilogb(inf/NaN) = 0x7fffffff (no signal is raised) + * return the binary exponent of x + * ilogb(+-0) = FP_ILOGB0 + * ilogb(+-inf) = INT_MAX + * ilogb(NaN) = FP_ILOGBNAN (no signal is raised) */ #include "math.h" @@ -22,21 +23,35 @@ int ilogb(double x) { int32_t hx,lx,ix; - GET_HIGH_WORD(hx,x); + GET_HIGH_WORD(hx, x); hx &= 0x7fffffff; - if(hx<0x00100000) { - GET_LOW_WORD(lx,x); - if((hx|lx)==0) - return 0x80000001; /* ilogb(0) = 0x80000001 */ - else /* subnormal x */ - if(hx==0) { - for (ix = -1043; lx>0; lx<<=1) ix -=1; - } else { - for (ix = -1022,hx<<=11; hx>0; hx<<=1) ix -=1; + + if (hx < 0x00100000) { + GET_LOW_WORD(lx, x); + if ((hx|lx)==0) /* +-0, ilogb(0) = FP_ILOGB0 */ + return FP_ILOGB0; + /* subnormal x */ + ix = -1043; + if (hx != 0) { + ix = -1022; + lx = (hx << 11); } - return ix; + /* each leading zero mantissa bit makes exponent smaller */ + for (; lx > 0; lx <<= 1) + ix--; + return ix; } - else if (hx<0x7ff00000) return (hx>>20)-1023; - else return 0x7fffffff; + + if (hx < 0x7ff00000) /* normal x */ + return (hx>>20) - 1023; + + if (FP_ILOGBNAN != (~0U >> 1)) { + GET_LOW_WORD(lx, x); + if (hx == 0x7ff00000 && lx == 0) /* +-inf */ + return ~0U >> 1; /* = INT_MAX */ + } + + /* NAN. ilogb(NAN) = FP_ILOGBNAN */ + return FP_ILOGBNAN; } libm_hidden_def(ilogb) diff --git a/test/math/Makefile.in b/test/math/Makefile.in index e801112c6..9ceb6c6d5 100644 --- a/test/math/Makefile.in +++ b/test/math/Makefile.in @@ -1,7 +1,8 @@ # uClibc math tests # Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball. -TESTS := basic-test rint signgam tst-definitions test-fpucw test-float test-ifloat test-double test-idouble +TESTS := basic-test tst-definitions test-fpucw test-float test-ifloat test-double test-idouble \ + rint signgam ilogb ifeq ($(UCLIBC_HAS_LONG_DOUBLE_MATH),y) TESTS += test-ldouble test-ildoubl compile_test else diff --git a/test/math/ilogb.c b/test/math/ilogb.c new file mode 100644 index 000000000..e439f8c37 --- /dev/null +++ b/test/math/ilogb.c @@ -0,0 +1,51 @@ +#include <math.h> +#include <stdlib.h> +#include <stdint.h> +#include <limits.h> +#include <stdio.h> + +#define check_d1(func, param, expected) \ +do { \ + int err; hex_union ur; hex_union up; \ + double result = func(param); up.f = param; ur.f = result; \ + errors += (err = (result != (expected))); \ + err \ + ? printf("FAIL: %s(%g/"HEXFMT")=%g/"HEXFMT" (expected %g)\n", \ + #func, (double)(param), (long long)up.hex, result, (long long)ur.hex, (double)(expected)) \ + : printf("PASS: %s(%g)=%g\n", #func, (double)(param), result); \ +} while (0) + +#define check_i1(func, param, expected) \ +do { \ + int err; hex_union up; \ + long long result = func(param); up.f = param; \ + errors += (err = (result != (expected))); \ + err \ + ? printf("FAIL: %s(%g/"HEXFMT")=%lld/%llu (expected %llu)\n", \ + #func, (double)(param), (long long)up.hex, result, result, (long long)(expected)) \ + : printf("PASS: %s(%g)=%lld/%llu\n", #func, (double)(param), result, result); \ +} while (0) + +#define HEXFMT "%08llx" +typedef union { + double f; + uint64_t hex; +} hex_union; + +double nan_value = 0.0; +int errors = 0; + +int main(void) +{ + nan_value /= nan_value; + + check_i1(ilogb, 0.0, FP_ILOGB0); + check_i1(ilogb, HUGE_VAL, INT_MAX); + check_i1(ilogb, nan_value, FP_ILOGBNAN); + check_i1(ilogbf, 0.0, FP_ILOGB0); + check_i1(ilogbf, HUGE_VALF, INT_MAX); + check_i1(ilogbf, nan_value, FP_ILOGBNAN); + + printf("Errors: %d\n", errors); + return errors; +} |