From c90cfc225baaf64af311f7e2953267e4de636205 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Ren=C3=A9=20Scharfe?= Date: Fri, 8 Oct 2021 06:04:42 +0200 Subject: test-mergesort: use repeatable random numbers MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Use MINSTD to generate pseudo-random numbers consistently instead of using rand(3), whose output can vary from system to system, and reset its seed before filling in the test values. This gives repeatable results across versions and systems, which simplifies sharing and comparing of results between developers. Signed-off-by: René Scharfe Signed-off-by: Junio C Hamano --- t/helper/test-mergesort.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/t/helper/test-mergesort.c b/t/helper/test-mergesort.c index 43ec74e2d3..ebf68f7de8 100644 --- a/t/helper/test-mergesort.c +++ b/t/helper/test-mergesort.c @@ -2,6 +2,12 @@ #include "cache.h" #include "mergesort.h" +static uint32_t minstd_rand(uint32_t *state) +{ + *state = (uint64_t)*state * 48271 % 2147483647; + return *state; +} + struct line { char *text; struct line *next; @@ -60,8 +66,9 @@ static void dist_sawtooth(int *arr, int n, int m) static void dist_rand(int *arr, int n, int m) { int i; + uint32_t seed = 1; for (i = 0; i < n; i++) - arr[i] = rand() % m; + arr[i] = minstd_rand(&seed) % m; } static void dist_stagger(int *arr, int n, int m) @@ -81,8 +88,9 @@ static void dist_plateau(int *arr, int n, int m) static void dist_shuffle(int *arr, int n, int m) { int i, j, k; + uint32_t seed = 1; for (i = j = 0, k = 1; i < n; i++) - arr[i] = (rand() % m) ? (j += 2) : (k += 2); + arr[i] = minstd_rand(&seed) % m ? (j += 2) : (k += 2); } #define DIST(name) { #name, dist_##name } -- cgit v1.2.3