provide an internal rand() replacement and use it in libmodplug/snd_fx.c

because SDL doesn't provide a rand() replacement..
icculus · Mar 20, 2021 · 4702d4a · 4702d4a
1 parent d0340e6
commit 4702d4a
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Showing 5 changed files with 24 additions and 4 deletions.
diff --git a/src/SDL_sound.c b/src/SDL_sound.c
@@ -798,6 +798,19 @@ Sint32 Sound_GetDuration(Sound_Sample *sample)
 
 /* Utility functions ... */
 
+/* The following uses the implementation suggested by
+ * the standard document, assumes RAND_MAX == 32767 */
+static unsigned long __Sound_seed = 1;
+int __Sound_rand(void)
+{
+    __Sound_seed = __Sound_seed * 1103515245 + 12345;
+    return (__Sound_seed / 65536) % 32768;
+}
+void __Sound_srand(unsigned int seed)
+{
+    __Sound_seed = seed;
+}
+
 #if !defined(HAVE_SDL_STRTOKR)
 /* Adapted from _PDCLIB_strtok() of PDClib library at
  * https://github.com/DevSolar/pdclib.git

diff --git a/src/SDL_sound_internal.h b/src/SDL_sound_internal.h
@@ -304,6 +304,12 @@ Uint32 __Sound_convertMsToBytePos(Sound_AudioInfo *info, Uint32 ms);
 extern char *SDL_strtokr(char *s1, const char *s2, char **saveptr);
 #endif
 
+/* SDL doesn't provide a rand() replacement */
+#define SDL_rand __Sound_rand
+#define SDL_srand __Sound_srand
+extern int SDL_rand(void);
+extern void SDL_srand(unsigned int seed);
+
 #endif /* defined _INCLUDE_SDL_SOUND_INTERNAL_H_ */
 
 /* end of SDL_sound_internal.h ... */

diff --git a/src/libmodplug/libmodplug.h b/src/libmodplug/libmodplug.h
@@ -83,6 +83,8 @@ typedef void VOID;
  *          Adam Goode       <adam@evdebs.org> (endian and char fixes for PPC)
 */
 
+extern void init_modplug_filters(void);
+
 #ifndef LPCBYTE
 typedef const BYTE * LPCBYTE;
 #endif

diff --git a/src/libmodplug/modplug.c b/src/libmodplug/modplug.c
@@ -9,10 +9,10 @@
 
 void ModPlug_Quit(void) { /* does nothing. */ }
 
-extern void init_modplug_filters(void);
 int ModPlug_Init(void)
 {
 	init_modplug_filters();
+	SDL_srand(SDL_GetTicks());
 	return 1;
 }
 

diff --git a/src/libmodplug/snd_fx.c b/src/libmodplug/snd_fx.c
@@ -5,7 +5,6 @@
 */
 
 #include "libmodplug.h"
-#include <stdlib.h> /* for rand() */
 #define SNDFX_C
 #include "tables.h"
 
@@ -523,13 +522,13 @@ void CSoundFile_NoteChange(CSoundFile *_this, UINT nChn, int note, BOOL bPorta,
 					// Volume Swing
 					if (penv->nVolSwing)
 					{
-						int d = ((LONG)penv->nVolSwing*(LONG)((rand() & 0xFF) - 0x7F)) / 128;
+						int d = ((LONG)penv->nVolSwing*(LONG)((SDL_rand() & 0xFF) - 0x7F)) / 128;
 						pChn->nVolSwing = (signed short)((d * pChn->nVolume + 1)/128);
 					}
 					// Pan Swing
 					if (penv->nPanSwing)
 					{
-						int d = ((LONG)penv->nPanSwing*(LONG)((rand() & 0xFF) - 0x7F)) / 128;
+						int d = ((LONG)penv->nPanSwing*(LONG)((SDL_rand() & 0xFF) - 0x7F)) / 128;
 						pChn->nPanSwing = (signed short)d;
 					}
 				}