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| #include <stdio.h> | |
| #include <stdint.h> | |
| #include <math.h> | |
| #define nl() printf("\n") | |
| #define fl_mark() printf("s/exp /mantissa\n"); | |
| #define is_finite(_fl) ((_fl & 0x7F800000) != 0x7F800000) | |
| #define is_normalized(_fl) is_finite(~(_fl)) | |
| void | |
| print_u32(void *obj) | |
| { | |
| if (!obj) return; | |
| uint32_t buf = *(uint32_t *)obj; | |
| for (uint32_t ct = 1 << 31; ct; ct >>= 1) { | |
| printf(buf & ct ? "1" : "0"); | |
| } | |
| } | |
| // exp is locked between -23 and 23 | |
| // handle more special cases | |
| // truncating and rounding | |
| void | |
| print_float(float fl) | |
| { | |
| const uint32_t buf = *(uint32_t *)&fl; | |
| int is_pos = !(buf & 1 << 31); | |
| if (!is_normalized(buf)) { | |
| if (buf & 0x007FFFFF) { | |
| printf("denormalized"); | |
| return; | |
| } | |
| } | |
| if (!is_finite(buf)) { | |
| printf("%s%s" | |
| , is_pos ? "" : "-" | |
| , buf & 0x007FFFFF ? "nan" : "inf"); | |
| return; | |
| } | |
| int exp = (uint8_t)(buf >> 23) - 127; | |
| uint32_t mantissa = buf & 0x007FFFFF | 0x00800000; | |
| uint32_t int_part = mantissa >> (23 - exp); | |
| if (exp < 0) { | |
| mantissa >>= -exp; | |
| int_part = exp = 0; | |
| } | |
| uint64_t mult = 1000000000000000000 >> 1; | |
| uint64_t dec_part = 0; | |
| for (uint32_t ct = 1 << (22 - exp); ct; ct >>= 1) { | |
| if (mantissa & ct) { | |
| dec_part += mult; | |
| // radix or whatev | |
| // inc max decimal places | |
| } | |
| mult >>= 1; | |
| } | |
| // round and truncate | |
| printf("%s%u.%018lu", is_pos ? "" : "-", int_part, dec_part); | |
| } | |
| int | |
| main(void) | |
| { | |
| print_float(INFINITY); nl(); | |
| print_float(NAN); nl(); | |
| print_float(-INFINITY); nl(); | |
| print_float(-NAN); nl(); | |
| nl(); | |
| print_float(0.); nl(); | |
| print_float(*(float *)&(uint32_t) { 0x00400000 }); nl(); | |
| nl(); | |
| print_float(1.); nl(); | |
| print_float(2.); nl(); | |
| print_float(-2.); nl(); | |
| print_float(45.); nl(); | |
| print_float(-45.5); nl(); | |
| print_float(30.125); nl(); | |
| print_float(30.03042145987018); nl(); | |
| nl(); | |
| print_float(0.5); nl(); | |
| print_float(0.12345); nl(); | |
| print_float(0.012345); nl(); | |
| print_float(0.000045); nl(); | |
| nl(); | |
| return 0; | |
| } |
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