mirror of
https://github.com/jart/cosmopolitan.git
synced 2025-02-01 03:53:33 +00:00
fa20edc44d
- Remove most __ASSEMBLER__ __LINKER__ ifdefs - Rename libc/intrin/bits.h to libc/serialize.h - Block pthread cancelation in fchmodat() polyfill - Remove `clang-format off` statements in third_party
33 lines
909 B
C
33 lines
909 B
C
#ifndef COSMOPOLITAN_LIBC_TINYMATH_MAGICU_H_
|
||
#define COSMOPOLITAN_LIBC_TINYMATH_MAGICU_H_
|
||
COSMOPOLITAN_C_START_
|
||
|
||
struct magicu {
|
||
uint32_t M;
|
||
uint32_t s;
|
||
};
|
||
|
||
struct magicu __magicu_get(uint32_t);
|
||
|
||
/**
|
||
* Performs fast division using precomputed magic for constant divisor.
|
||
*
|
||
* @param x is unsigned integer that shall be divided
|
||
* @param d should be `__magicu_get(y)` if computing `x / y`
|
||
* @return result of unsigned integer division
|
||
*/
|
||
forceinline uint32_t __magicu_div(uint32_t x, struct magicu d) {
|
||
return ((((uint64_t)x * d.M) >> 32) + ((d.s & 64) ? x : 0)) >> (d.s & 63);
|
||
}
|
||
|
||
/**
|
||
* Checks if 𝑑 contains a valid initialized divisor.
|
||
*/
|
||
static inline bool32 __magicu_valid(struct magicu d) {
|
||
if (!d.M && !d.s) return false; /* uninitialized */
|
||
if (d.s & ~(64 | 63)) return false; /* corrupted */
|
||
return true;
|
||
}
|
||
|
||
COSMOPOLITAN_C_END_
|
||
#endif /* COSMOPOLITAN_LIBC_TINYMATH_MAGICU_H_ */
|