From 67396848cb5e3e55385a466d7a24a4f68d0a6c9c Mon Sep 17 00:00:00 2001 From: Christian Heller Date: Sun, 26 May 2013 04:40:24 +0200 Subject: [PATCH] Use own pseudo-random number generator to ensure portable predictability. --- roguelike.c | 14 ++++++++++++-- roguelike.h | 1 + 2 files changed, 13 insertions(+), 2 deletions(-) diff --git a/roguelike.c b/roguelike.c index cc218a3..7b2d159 100644 --- a/roguelike.c +++ b/roguelike.c @@ -8,6 +8,16 @@ #include "roguelike.h" #include "keybindings.h" +static uint32_t seed = 0; + +uint16_t rrand() { +// Pseudo-random number generator (LGC algorithm). Use instead of rand() to ensure portable predictability. + uint32_t a = 1103515245; // Values for a and b as recommended by POSIX.1-2001 (see man page rand(3)). + uint16_t b = 12345; + uint32_t mod = 2147483648; + seed = ((seed * a) + b) % mod; + return (seed / 65536); } // Ignore least significant 16 bits (they are less random). + void toggle_window (struct WinMeta * win_meta, struct Win * win) { // Toggle display of window win. if (0 != win->curses) @@ -43,7 +53,7 @@ struct Map init_map () { for (y = 0; y < map.height; y++) for (x = 0; x < map.width; x++) { terrain = '.'; - ran = rand(); + ran = rrand(); if ( 0 == ran % ((x*x) / 3 + 1) || 0 == ran % ((y*y) / 3 + 1) || 0 == ran % ((map.width - x - 1) * (map.width - x - 1) / 3 + 1) @@ -66,7 +76,7 @@ void map_scroll (struct Map * map, char dir) { void next_turn (struct World * world) { // Increment turn and move enemy. world->turn++; - char d = rand() % 5; + char d = rrand() % 5; char ty = world->monster->y; char tx = world->monster->x; if (1 == d) diff --git a/roguelike.h b/roguelike.h index 668d52c..650ddc1 100644 --- a/roguelike.h +++ b/roguelike.h @@ -22,6 +22,7 @@ struct Monster { uint16_t y; uint16_t x; }; +uint16_t rrand(); void toggle_window (struct WinMeta *, struct Win *); void growshrink_active_window (struct WinMeta *, char); struct Map init_map (); -- 2.30.2