diff options
Diffstat (limited to 'lib/builtins/floatuntidf.c')
| -rw-r--r-- | lib/builtins/floatuntidf.c | 94 |
1 files changed, 44 insertions, 50 deletions
diff --git a/lib/builtins/floatuntidf.c b/lib/builtins/floatuntidf.c index 729048883..0f2f6f279 100644 --- a/lib/builtins/floatuntidf.c +++ b/lib/builtins/floatuntidf.c @@ -21,59 +21,53 @@ * tu_int is a 128 bit integral type */ -/* seee eeee eeee mmmm mmmm mmmm mmmm mmmm | mmmm mmmm mmmm mmmm mmmm mmmm mmmm mmmm */ +/* seee eeee eeee mmmm mmmm mmmm mmmm mmmm | mmmm mmmm mmmm mmmm mmmm mmmm mmmm + * mmmm */ -COMPILER_RT_ABI double -__floatuntidf(tu_int a) -{ - if (a == 0) - return 0.0; - const unsigned N = sizeof(tu_int) * CHAR_BIT; - int sd = N - __clzti2(a); /* number of significant digits */ - int e = sd - 1; /* exponent */ - if (sd > DBL_MANT_DIG) - { - /* start: 0000000000000000000001xxxxxxxxxxxxxxxxxxxxxxPQxxxxxxxxxxxxxxxxxx - * finish: 000000000000000000000000000000000000001xxxxxxxxxxxxxxxxxxxxxxPQR - * 12345678901234567890123456 - * 1 = msb 1 bit - * P = bit DBL_MANT_DIG-1 bits to the right of 1 - * Q = bit DBL_MANT_DIG bits to the right of 1 - * R = "or" of all bits to the right of Q - */ - switch (sd) - { - case DBL_MANT_DIG + 1: - a <<= 1; - break; - case DBL_MANT_DIG + 2: - break; - default: - a = (a >> (sd - (DBL_MANT_DIG+2))) | - ((a & ((tu_int)(-1) >> ((N + DBL_MANT_DIG+2) - sd))) != 0); - }; - /* finish: */ - a |= (a & 4) != 0; /* Or P into R */ - ++a; /* round - this step may add a significant bit */ - a >>= 2; /* dump Q and R */ - /* a is now rounded to DBL_MANT_DIG or DBL_MANT_DIG+1 bits */ - if (a & ((tu_int)1 << DBL_MANT_DIG)) - { - a >>= 1; - ++e; - } - /* a is now rounded to DBL_MANT_DIG bits */ +COMPILER_RT_ABI double __floatuntidf(tu_int a) { + if (a == 0) + return 0.0; + const unsigned N = sizeof(tu_int) * CHAR_BIT; + int sd = N - __clzti2(a); /* number of significant digits */ + int e = sd - 1; /* exponent */ + if (sd > DBL_MANT_DIG) { + /* start: 0000000000000000000001xxxxxxxxxxxxxxxxxxxxxxPQxxxxxxxxxxxxxxxxxx + * finish: 000000000000000000000000000000000000001xxxxxxxxxxxxxxxxxxxxxxPQR + * 12345678901234567890123456 + * 1 = msb 1 bit + * P = bit DBL_MANT_DIG-1 bits to the right of 1 + * Q = bit DBL_MANT_DIG bits to the right of 1 + * R = "or" of all bits to the right of Q + */ + switch (sd) { + case DBL_MANT_DIG + 1: + a <<= 1; + break; + case DBL_MANT_DIG + 2: + break; + default: + a = (a >> (sd - (DBL_MANT_DIG + 2))) | + ((a & ((tu_int)(-1) >> ((N + DBL_MANT_DIG + 2) - sd))) != 0); + }; + /* finish: */ + a |= (a & 4) != 0; /* Or P into R */ + ++a; /* round - this step may add a significant bit */ + a >>= 2; /* dump Q and R */ + /* a is now rounded to DBL_MANT_DIG or DBL_MANT_DIG+1 bits */ + if (a & ((tu_int)1 << DBL_MANT_DIG)) { + a >>= 1; + ++e; } - else - { - a <<= (DBL_MANT_DIG - sd); - /* a is now rounded to DBL_MANT_DIG bits */ - } - double_bits fb; - fb.u.s.high = ((e + 1023) << 20) | /* exponent */ + /* a is now rounded to DBL_MANT_DIG bits */ + } else { + a <<= (DBL_MANT_DIG - sd); + /* a is now rounded to DBL_MANT_DIG bits */ + } + double_bits fb; + fb.u.s.high = ((e + 1023) << 20) | /* exponent */ ((su_int)(a >> 32) & 0x000FFFFF); /* mantissa-high */ - fb.u.s.low = (su_int)a; /* mantissa-low */ - return fb.f; + fb.u.s.low = (su_int)a; /* mantissa-low */ + return fb.f; } #endif /* CRT_HAS_128BIT */ |