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4096-wise thiersort2

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This commit is contained in:
Richard Thier 2025-09-27 01:43:55 +02:00
parent 76001efd98
commit f4e4db43f9
1 changed files with 7 additions and 7 deletions
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14
thiersort2.h
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@ -42,7 +42,7 @@ static inline uint32_t witch_bucket(uint32_t key) {
uint32_t witch_base = (key <= 2) ? 0 : (as.u >> 23) - 128; // 0, [127..159] -> [0..31] uint32_t witch_base = (key <= 2) ? 0 : (as.u >> 23) - 128; // 0, [127..159] -> [0..31]
// return witch_base * 8 + ((as.u >> (23 - 3)) & 7); // 0..255 // return witch_base * 8 + ((as.u >> (23 - 3)) & 7); // 0..255
return witch_base * 64 + ((as.u >> (23 - 6)) & 63); // 0..2047 return witch_base * 128 + ((as.u >> (23 - 7)) & 127); // 0..2047
/* Alternative (but I measure it being worse): /* Alternative (but I measure it being worse):
return (as.u >> 23); return (as.u >> 23);
*/ */
@ -57,8 +57,8 @@ static inline uint32_t witch_bucket(uint32_t key) {
* @param rstate Create with sch_rand_state rstate = schwab_rand_state(junk_uint32_t); * @param rstate Create with sch_rand_state rstate = schwab_rand_state(junk_uint32_t);
*/ */
static inline void thiersort2(uint32_t *arr, uint32_t *temparr, int n, sch_rand_state *rstate) { static inline void thiersort2(uint32_t *arr, uint32_t *temparr, int n, sch_rand_state *rstate) {
int bucket[2048]; /* Inclusive */ int bucket[4096]; /* Inclusive */
int bucket_end[2048]; /* Not inclusive */ int bucket_end[4096]; /* Not inclusive */
/* Check if need to sort at all - needed for invariants later */ /* Check if need to sort at all - needed for invariants later */
if(n < 2) { if(n < 2) {
@ -67,7 +67,7 @@ static inline void thiersort2(uint32_t *arr, uint32_t *temparr, int n, sch_rand_
/* Count */ /* Count */
#pragma GCC unroll 64 #pragma GCC unroll 64
for(int i = 0; i < 2048; ++i) { for(int i = 0; i < 4096; ++i) {
bucket[i] = 0; bucket[i] = 0;
} }
#pragma GCC unroll 64 #pragma GCC unroll 64
@ -78,14 +78,14 @@ static inline void thiersort2(uint32_t *arr, uint32_t *temparr, int n, sch_rand_
/* Prefix sum (like in Magyarsort) */ /* Prefix sum (like in Magyarsort) */
uint32_t prev = 0; uint32_t prev = 0;
#pragma GCC unroll 4 #pragma GCC unroll 4
for (int i = 0; i < 2048; i++) { for (int i = 0; i < 4096; i++) {
bucket[i] += prev; bucket[i] += prev;
prev = bucket[i]; prev = bucket[i];
} }
/* Save end-offsets */ /* Save end-offsets */
#pragma GCC unroll 64 #pragma GCC unroll 64
for(int i = 0; i < 2048; ++i) { for(int i = 0; i < 4096; ++i) {
bucket_end[i] = bucket[i]; bucket_end[i] = bucket[i];
} }
@ -102,7 +102,7 @@ static inline void thiersort2(uint32_t *arr, uint32_t *temparr, int n, sch_rand_
/* temparr -> arr each bucket and sort them in-place */ /* temparr -> arr each bucket and sort them in-place */
#pragma GCC unroll 64 #pragma GCC unroll 64
for(int b = 0; b < 2048; ++b) { for(int b = 0; b < 4096; ++b) {
int begin = bucket[b]; int begin = bucket[b];
int end = bucket_end[b]; int end = bucket_end[b];