diff options
| -rw-r--r-- | bits.c | 70 |
1 files changed, 22 insertions, 48 deletions
@@ -183,67 +183,41 @@ int leftBitCount(int x) { * Difficulty: 4 */ unsigned float_i2f(int x) { - int sign; - int mag; - int p; - int t; - int sig; - int frac; - int shift; - int rest; - int half; - int result; - - if (x == 0) - return 0u; + unsigned a; + unsigned sign; + unsigned sig; + int p; + int s; - if (x == ~0x7FFFFFFF) - return 0xCF000000u; + if (!x) + return 0; - sign = 0; if (x < 0) { - sign = 1; - mag = -x; + sign = 0x80000000u; + a = ~x; + a = a + 1; } else { - mag = x; + a = x; + sign = 0; } + sig = a; p = 0; - t = mag; - while (t > 1) { - t = t >> 1; + while (sig >> 1) { + sig = sig >> 1; p = p + 1; } if (p < 24) { - sig = mag << (23 - p); + sig = a << (23 - p); } else { - shift = p - 23; - sig = mag >> shift; - - rest = mag - (sig << shift); - half = 1 << (shift - 1); - - if (rest > half) { - sig = sig + 1; - } else if (rest == half) { - if (sig & 1) - sig = sig + 1; - } - - if (sig >> 24) { - sig = sig >> 1; - p = p + 1; - } + s = p - 23; + sig = (a + (1u << (s - 1)) - 1u + + ((a >> s) & 1u)) >> s; + p = p + (sig >> 24); } - frac = sig & 0x7FFFFF; - result = ((p + 127) << 23) | frac; - - if (sign) - return 0x80000000u | result; - - return result; + return sign | ((p + 127) << 23) | (sig & 0x7FFFFF); } /* @@ -251,7 +225,7 @@ unsigned float_i2f(int x) { * floating point argument f. * Both the argument and result are passed as unsigned int's, but * they are to be interpreted as the bit-level representation of - * single-precision floating point values. + * single-precision floating point values.p * When argument is NaN, return argument * Legal ops: & >> << | if > < >= <= ! ~ else + == * Max ops: 30 |