Added SDL_srand(), SDL_rand(), and SDL_rand_r() (thanks @JKaniarz!)

These are simple random functions that should not be used for serious random number generation.

Fixes https://github.com/libsdl-org/SDL/issues/4968

VisualC-GDK/SDL/SDL.vcxproj

@@ -785,6 +785,7 @@
       <PrecompiledHeader>NotUsing</PrecompiledHeader>
     </MASM>
     <ClCompile Include="..\..\src\stdlib\SDL_qsort.c" />
+    <ClCompile Include="..\..\src\stdlib\SDL_random.c" />
     <ClCompile Include="..\..\src\stdlib\SDL_stdlib.c" />
     <ClCompile Include="..\..\src\stdlib\SDL_string.c" />
     <ClCompile Include="..\..\src\stdlib\SDL_strtokr.c" />

VisualC-GDK/SDL/SDL.vcxproj.filters

@@ -160,6 +160,7 @@
     <ClCompile Include="..\..\src\stdlib\SDL_memset.c" />
     <ClCompile Include="..\..\src\stdlib\SDL_mslibc.c" />
     <ClCompile Include="..\..\src\stdlib\SDL_qsort.c" />
+    <ClCompile Include="..\..\src\stdlib\SDL_random.c" />
     <ClCompile Include="..\..\src\stdlib\SDL_stdlib.c" />
     <ClCompile Include="..\..\src\stdlib\SDL_string.c" />
     <ClCompile Include="..\..\src\stdlib\SDL_strtokr.c" />

VisualC-WinRT/SDL-UWP.vcxproj

@@ -442,6 +442,7 @@
       <PrecompiledHeader>NotUsing</PrecompiledHeader>
     </MASM>
     <ClCompile Include="..\src\stdlib\SDL_qsort.c" />
+    <ClCompile Include="..\src\stdlib\SDL_random.c" />
     <ClCompile Include="..\src\stdlib\SDL_stdlib.c" />
     <ClCompile Include="..\src\stdlib\SDL_string.c" />
     <ClCompile Include="..\src\stdlib\SDL_strtokr.c" />

VisualC-WinRT/SDL-UWP.vcxproj.filters

@@ -771,6 +771,9 @@
     <ClCompile Include="..\src\stdlib\SDL_qsort.c">
       <Filter>Source Files</Filter>
     </ClCompile>
+    <ClCompile Include="..\src\stdlib\SDL_random.c">
+      <Filter>Source Files</Filter>
+    </ClCompile>
     <ClCompile Include="..\src\stdlib\SDL_stdlib.c">
       <Filter>Source Files</Filter>
     </ClCompile>

VisualC/SDL/SDL.vcxproj

@@ -640,6 +640,7 @@
       <PrecompiledHeader>NotUsing</PrecompiledHeader>
     </MASM>
     <ClCompile Include="..\..\src\stdlib\SDL_qsort.c" />
+    <ClCompile Include="..\..\src\stdlib\SDL_random.c" />
     <ClCompile Include="..\..\src\stdlib\SDL_stdlib.c" />
     <ClCompile Include="..\..\src\stdlib\SDL_string.c" />
     <ClCompile Include="..\..\src\stdlib\SDL_strtokr.c" />

VisualC/SDL/SDL.vcxproj.filters

@@ -1393,6 +1393,9 @@
     <ClCompile Include="..\..\src\stdlib\SDL_qsort.c">
       <Filter>stdlib</Filter>
     </ClCompile>
+    <ClCompile Include="..\..\src\stdlib\SDL_random.c">
+      <Filter>stdlib</Filter>
+    </ClCompile>
     <ClCompile Include="..\..\src\stdlib\SDL_stdlib.c">
       <Filter>stdlib</Filter>
     </ClCompile>

Xcode/SDL/SDL.xcodeproj/project.pbxproj

@@ -383,6 +383,9 @@
 		E4F7981C2AD8D85500669F54 /* SDL_dynapi_unsupported.h in Headers */ = {isa = PBXBuildFile; fileRef = E4F7981B2AD8D85500669F54 /* SDL_dynapi_unsupported.h */; };
 		E4F7981E2AD8D86A00669F54 /* SDL_render_unsupported.c in Sources */ = {isa = PBXBuildFile; fileRef = E4F7981D2AD8D86A00669F54 /* SDL_render_unsupported.c */; };
 		E4F798202AD8D87F00669F54 /* SDL_video_unsupported.c in Sources */ = {isa = PBXBuildFile; fileRef = E4F7981F2AD8D87F00669F54 /* SDL_video_unsupported.c */; };
+		F310138D2C1F2CB700FBE946 /* SDL_getenv_c.h in Headers */ = {isa = PBXBuildFile; fileRef = F310138A2C1F2CB700FBE946 /* SDL_getenv_c.h */; };
+		F310138E2C1F2CB700FBE946 /* SDL_random.c in Sources */ = {isa = PBXBuildFile; fileRef = F310138B2C1F2CB700FBE946 /* SDL_random.c */; };
+		F310138F2C1F2CB700FBE946 /* SDL_sysstdlib.h in Headers */ = {isa = PBXBuildFile; fileRef = F310138C2C1F2CB700FBE946 /* SDL_sysstdlib.h */; };
 		F316ABD82B5C3185002EF551 /* SDL_memset.c in Sources */ = {isa = PBXBuildFile; fileRef = F316ABD62B5C3185002EF551 /* SDL_memset.c */; };
 		F316ABD92B5C3185002EF551 /* SDL_memcpy.c in Sources */ = {isa = PBXBuildFile; fileRef = F316ABD72B5C3185002EF551 /* SDL_memcpy.c */; };
 		F316ABDB2B5CA721002EF551 /* SDL_memmove.c in Sources */ = {isa = PBXBuildFile; fileRef = F316ABDA2B5CA721002EF551 /* SDL_memmove.c */; };
@@ -909,6 +912,9 @@
 		E4F7981B2AD8D85500669F54 /* SDL_dynapi_unsupported.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = SDL_dynapi_unsupported.h; sourceTree = "<group>"; };
 		E4F7981D2AD8D86A00669F54 /* SDL_render_unsupported.c */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.c; path = SDL_render_unsupported.c; sourceTree = "<group>"; };
 		E4F7981F2AD8D87F00669F54 /* SDL_video_unsupported.c */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.c; path = SDL_video_unsupported.c; sourceTree = "<group>"; };
+		F310138A2C1F2CB700FBE946 /* SDL_getenv_c.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = SDL_getenv_c.h; sourceTree = "<group>"; };
+		F310138B2C1F2CB700FBE946 /* SDL_random.c */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.c; path = SDL_random.c; sourceTree = "<group>"; };
+		F310138C2C1F2CB700FBE946 /* SDL_sysstdlib.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = SDL_sysstdlib.h; sourceTree = "<group>"; };
 		F316ABD62B5C3185002EF551 /* SDL_memset.c */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.c; path = SDL_memset.c; sourceTree = "<group>"; };
 		F316ABD72B5C3185002EF551 /* SDL_memcpy.c */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.c; path = SDL_memcpy.c; sourceTree = "<group>"; };
 		F316ABDA2B5CA721002EF551 /* SDL_memmove.c */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.c; path = SDL_memmove.c; sourceTree = "<group>"; };
@@ -2035,6 +2041,7 @@
 			children = (
 				F3973FA128A59BDD00B84553 /* SDL_crc16.c */,
 				F395BF6425633B2400942BFF /* SDL_crc32.c */,
+				F310138A2C1F2CB700FBE946 /* SDL_getenv_c.h */,
 				A7D8A8D423E2514000DCD162 /* SDL_getenv.c */,
 				A7D8A8D323E2514000DCD162 /* SDL_iconv.c */,
 				A7D8A8D923E2514000DCD162 /* SDL_malloc.c */,
@@ -2042,9 +2049,11 @@
 				F316ABDA2B5CA721002EF551 /* SDL_memmove.c */,
 				F316ABD62B5C3185002EF551 /* SDL_memset.c */,
 				A7D8A8D723E2514000DCD162 /* SDL_qsort.c */,
+				F310138B2C1F2CB700FBE946 /* SDL_random.c */,
 				A7D8A8D823E2514000DCD162 /* SDL_stdlib.c */,
 				A7D8A8D523E2514000DCD162 /* SDL_string.c */,
 				A7D8A8D623E2514000DCD162 /* SDL_strtokr.c */,
+				F310138C2C1F2CB700FBE946 /* SDL_sysstdlib.h */,
 				F3973FA028A59BDD00B84553 /* SDL_vacopy.h */,
 			);
 			path = stdlib;
@@ -2291,6 +2300,7 @@
 			buildActionMask = 2147483647;
 			files = (
 				F3F7D9812933074E00816151 /* SDL.h in Headers */,
+				F310138D2C1F2CB700FBE946 /* SDL_getenv_c.h in Headers */,
 				A7D8B39E23E2514200DCD162 /* SDL_RLEaccel_c.h in Headers */,
 				F3F7D9C52933074E00816151 /* SDL_assert.h in Headers */,
 				A7D8B61723E2514300DCD162 /* SDL_assert_c.h in Headers */,
@@ -2439,6 +2449,7 @@
 				A7D8B98C23E2514400DCD162 /* SDL_shaders_metal_ios.h in Headers */,
 				A7D8B99B23E2514400DCD162 /* SDL_shaders_metal_macos.h in Headers */,
 				A7D8B9A123E2514400DCD162 /* SDL_shaders_metal_tvos.h in Headers */,
+				F310138F2C1F2CB700FBE946 /* SDL_sysstdlib.h in Headers */,
 				F3F7D8F52933074E00816151 /* SDL_stdinc.h in Headers */,
 				F362B91B2B3349E200D30B94 /* SDL_steam_virtual_gamepad.h in Headers */,
 				A7D8BBC723E2561500DCD162 /* SDL_steamcontroller.h in Headers */,
@@ -2869,6 +2880,7 @@
 				0000A4DA2F45A31DC4F00000 /* SDL_sysmain_callbacks.m in Sources */,
 				000028F8113A53F4333E0000 /* SDL_main_callbacks.c in Sources */,
 				000098E9DAA43EF6FF7F0000 /* SDL_camera.c in Sources */,
+				F310138E2C1F2CB700FBE946 /* SDL_random.c in Sources */,
 				00001B2471F503DD3C1B0000 /* SDL_camera_dummy.c in Sources */,
 				00002B20A48E055EB0350000 /* SDL_camera_coremedia.m in Sources */,
 				000080903BC03006F24E0000 /* SDL_filesystem.c in Sources */,

include/SDL3/SDL_stdinc.h

@@ -1259,6 +1259,52 @@ extern SDL_DECLSPEC int SDLCALL SDL_vswprintf(SDL_OUT_Z_CAP(maxlen) wchar_t *tex
 extern SDL_DECLSPEC int SDLCALL SDL_asprintf(char **strp, SDL_PRINTF_FORMAT_STRING const char *fmt, ...) SDL_PRINTF_VARARG_FUNC(2);
 extern SDL_DECLSPEC int SDLCALL SDL_vasprintf(char **strp, SDL_PRINTF_FORMAT_STRING const char *fmt, va_list ap) SDL_PRINTF_VARARG_FUNCV(2);
 
+/**
+ * Seed the pseudo-random number generator
+ *
+ * \param seed the value to use as a random number seed, or 0 to use SDL_GetPerformanceCounter()
+ *
+ * \threadsafety This should be called on the same thread that calls SDL_rand()
+ *
+ * \since This function is available since SDL 3.0.0.
+ *
+ * \sa SDL_rand
+ */
+extern SDL_DECLSPEC void SDLCALL SDL_srand(Uint64 seed);
+
+/**
+ * Get a pseudo-random number.
+ *
+ * There are no guarantees as to the quality of the random sequence produced, and this should not be used for cryptography or anything that requires good random distribution. There are many random number libraries available with different characteristics and you should pick one of those to meet any serious needs.
+ *
+ * \returns a random value in the range of [0-SDL_MAX_UINT32]
+ *
+ * \threadsafety All calls should be from from a single thread, use SDL_rand_r() when using multiple threads.
+ *
+ * \since This function is available since SDL 3.0.0.
+ *
+ * \sa SDL_rand_r
+ * \sa SDL_srand
+ */
+extern SDL_DECLSPEC Uint32 SDLCALL SDL_rand(void);
+
+/**
+ * Get a pseudo-random number.
+ *
+ * There are no guarantees as to the quality of the random sequence produced, and this should not be used for cryptography or anything that requires good random distribution. There are many random number libraries available with different characteristics and you should pick one of those to meet any serious needs.
+ *
+ * \param state a pointer to a 64-bit seed value that will be updated with each call to SDL_rand_r(). If the value of the seed is 0, it will be initialized with SDL_GetPerformanceCounter().
+ * \returns a random value in the range of [0-SDL_MAX_UINT32], or 0 if state is NULL.
+ *
+ * \threadsafety This can be called from any thread, however each thread should pass its own state pointer.
+ *
+ * \since This function is available since SDL 3.0.0.
+ *
+ * \sa SDL_rand
+ */
+extern SDL_DECLSPEC Uint32 SDLCALL SDL_rand_r(Uint64 *state);
+
+
 #ifndef SDL_PI_D
 #define SDL_PI_D   3.141592653589793238462643383279502884       /**< pi (double) */
 #endif

src/dynapi/SDL_dynapi.sym

@@ -955,6 +955,8 @@ SDL3_0.0.0 {
     SDL_powf;
     SDL_qsort;
     SDL_qsort_r;
+    SDL_rand;
+    SDL_rand_r;
     SDL_realloc;
     SDL_round;
     SDL_roundf;
@@ -966,6 +968,7 @@ SDL3_0.0.0 {
     SDL_snprintf;
     SDL_sqrt;
     SDL_sqrtf;
+    SDL_srand;
     SDL_sscanf;
     SDL_strcasecmp;
     SDL_strcasestr;

src/dynapi/SDL_dynapi_overrides.h

@@ -980,6 +980,8 @@
 #define SDL_powf SDL_powf_REAL
 #define SDL_qsort SDL_qsort_REAL
 #define SDL_qsort_r SDL_qsort_r_REAL
+#define SDL_rand SDL_rand_REAL
+#define SDL_rand_r SDL_rand_r_REAL
 #define SDL_realloc SDL_realloc_REAL
 #define SDL_round SDL_round_REAL
 #define SDL_roundf SDL_roundf_REAL
@@ -991,6 +993,7 @@
 #define SDL_snprintf    SDL_snprintf_REAL
 #define SDL_sqrt SDL_sqrt_REAL
 #define SDL_sqrtf SDL_sqrtf_REAL
+#define SDL_srand SDL_srand_REAL
 #define SDL_sscanf  SDL_sscanf_REAL
 #define SDL_strcasecmp SDL_strcasecmp_REAL
 #define SDL_strcasestr SDL_strcasestr_REAL

src/dynapi/SDL_dynapi_procs.h

@@ -989,6 +989,8 @@ SDL_DYNAPI_PROC(double,SDL_pow,(double a, double b),(a,b),return)
 SDL_DYNAPI_PROC(float,SDL_powf,(float a, float b),(a,b),return)
 SDL_DYNAPI_PROC(void,SDL_qsort,(void *a, size_t b, size_t c, SDL_CompareCallback d),(a,b,c,d),)
 SDL_DYNAPI_PROC(void,SDL_qsort_r,(void *a, size_t b, size_t c, SDL_CompareCallback_r d, void *e),(a,b,c,d,e),)
+SDL_DYNAPI_PROC(Uint32,SDL_rand,(void),(),return)
+SDL_DYNAPI_PROC(Uint32,SDL_rand_r,(Uint64 *a),(a),return)
 SDL_DYNAPI_PROC(void*,SDL_realloc,(void *a, size_t b),(a,b),return)
 SDL_DYNAPI_PROC(double,SDL_round,(double a),(a),return)
 SDL_DYNAPI_PROC(float,SDL_roundf,(float a),(a),return)
@@ -999,6 +1001,7 @@ SDL_DYNAPI_PROC(double,SDL_sin,(double a),(a),return)
 SDL_DYNAPI_PROC(float,SDL_sinf,(float a),(a),return)
 SDL_DYNAPI_PROC(double,SDL_sqrt,(double a),(a),return)
 SDL_DYNAPI_PROC(float,SDL_sqrtf,(float a),(a),return)
+SDL_DYNAPI_PROC(void,SDL_srand,(Uint64 a),(a),)
 SDL_DYNAPI_PROC(int,SDL_strcasecmp,(const char *a, const char *b),(a,b),return)
 SDL_DYNAPI_PROC(char*,SDL_strcasestr,(const char *a, const char *b),(a,b),return)
 SDL_DYNAPI_PROC(char*,SDL_strchr,(const char *a, int b),(a,b),return)

src/stdlib/SDL_random.c

@@ -0,0 +1,80 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2024 Sam Lantinga <slouken@libsdl.org>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+#include "SDL_internal.h"
+
+/* This file contains portable random functions for SDL */
+
+static Uint64 SDL_rand_state;
+
+void SDL_srand(Uint64 seed)
+{
+    SDL_rand_state = seed;
+}
+
+Uint32 SDL_rand(void)
+{
+	return SDL_rand_r(&SDL_rand_state);
+}
+
+/*
+ * Return a number between [0, n)
+ * Fast but slightly biased. Don't run your casino with this.
+ */
+Sint32 SDL_rand_n(Sint32 n)
+{
+	// On 32-bit arch, the compiler will optimize to a single 32-bit multiply
+	Uint64 val = (Uint64)SDL_rand() * n;
+	return (Sint32)(val >> 32);
+}
+
+/*
+ * Random float in range [0,1)
+ */
+float SDL_rand_float(void)
+{
+	return (SDL_rand() >> (32-24)) * 0x1p-24f;
+}
+
+/* A fast psuedo-random number generator.
+ * Not suitable for cryptography or gambling
+ */
+Uint32 SDL_rand_r(Uint64 *state)
+{
+    if (!state) {
+        return 0;
+    }
+
+    if (!*state) {
+        *state = SDL_GetPerformanceCounter();
+    }
+
+	// Multiplier from Table 6 of
+	// Steele GL, Vigna S. Computationally easy, spectrally good multipliers
+	// for congruential pseudorandom number generators.
+	// Softw Pract Exper. 2022;52(2):443-458. doi: 10.1002/spe.3030
+
+	// 32-bit 'a' improves performance on 32-bit architectures
+	// 'c' can be any odd number, but < 256 generates smaller code on some arch
+	*state = *state * 0xf9b25d65ul + 0xFD;
+
+	// Only return top 32 bits because they have a longer period
+	return (Uint32)(*state >> 32);
+}

test/checkkeysthreads.c

@@ -23,7 +23,6 @@
 #include <emscripten/emscripten.h>
 #endif
 
-#include <stdio.h>
 #include <stdlib.h>
 
 static int done;
@@ -172,8 +171,7 @@ static void loop(void)
     /* Check for events */
     /*SDL_WaitEvent(&event); emscripten does not like waiting*/
 
-    (void)fprintf(stderr, "starting loop\n");
-    (void)fflush(stderr);
+    SDL_Log("starting loop\n");
     while (!done && SDL_WaitEvent(&event)) {
         SDL_Log("Got event type: %" SDL_PRIu32 "\n", event.type);
         switch (event.type) {
@@ -189,8 +187,7 @@ static void loop(void)
             break;
         case SDL_EVENT_MOUSE_BUTTON_DOWN:
             /* Left button quits the app, other buttons toggles text input */
-            (void)fprintf(stderr, "mouse button down button: %d (LEFT=%d)\n", event.button.button, SDL_BUTTON_LEFT);
-            (void)fflush(stderr);
+            SDL_Log("mouse button down button: %d (LEFT=%d)\n", event.button.button, SDL_BUTTON_LEFT);
             if (event.button.button == SDL_BUTTON_LEFT) {
                 done = 1;
             } else {
@@ -209,11 +206,9 @@ static void loop(void)
         default:
             break;
         }
-        (void)fprintf(stderr, "waiting new event\n");
-        (void)fflush(stderr);
+       SDL_Log("waiting new event\n");
     }
-    (void)fprintf(stderr, "exiting event loop\n");
-    (void)fflush(stderr);
+    SDL_Log("exiting event loop\n");
 #ifdef SDL_PLATFORM_EMSCRIPTEN
     if (done) {
         emscripten_cancel_main_loop();
@@ -228,12 +223,11 @@ static int SDLCALL ping_thread(void *ptr)
     SDL_Event sdlevent;
     SDL_memset(&sdlevent, 0, sizeof(SDL_Event));
     for (cnt = 0; cnt < 10; ++cnt) {
-        (void)fprintf(stderr, "sending event (%d/%d) from thread.\n", cnt + 1, 10);
-        (void)fflush(stderr);
+        SDL_Log("sending event (%d/%d) from thread.\n", cnt + 1, 10);
         sdlevent.type = SDL_EVENT_KEY_DOWN;
         sdlevent.key.keysym.sym = SDLK_1;
         SDL_PushEvent(&sdlevent);
-        SDL_Delay(1000 + rand() % 1000);
+        SDL_Delay(1000 + SDL_rand() % 1000);
     }
     return cnt;
 }

test/testdraw.c

@@ -20,9 +20,6 @@
 #include <emscripten/emscripten.h>
 #endif
 
-#include <stdlib.h>
-#include <time.h>
-
 #define NUM_OBJECTS 100
 
 static SDLTest_CommonState *state;
@@ -75,8 +72,8 @@ static void DrawPoints(SDL_Renderer *renderer)
         SDL_SetRenderDrawColor(renderer, 255, (Uint8)current_color,
                                (Uint8)current_color, (Uint8)current_alpha);
 
-        x = (float)(rand() % viewport.w);
-        y = (float)(rand() % viewport.h);
+        x = (float)(SDL_rand() % viewport.w);
+        y = (float)(SDL_rand() % viewport.h);
         SDL_RenderPoint(renderer, x, y);
     }
 }
@@ -123,10 +120,10 @@ static void DrawLines(SDL_Renderer *renderer)
             SDL_RenderLine(renderer, 0.0f, (float)(viewport.h / 2), (float)(viewport.w - 1), (float)(viewport.h / 2));
             SDL_RenderLine(renderer, (float)(viewport.w / 2), 0.0f, (float)(viewport.w / 2), (float)(viewport.h - 1));
         } else {
-            x1 = (float)((rand() % (viewport.w * 2)) - viewport.w);
-            x2 = (float)((rand() % (viewport.w * 2)) - viewport.w);
-            y1 = (float)((rand() % (viewport.h * 2)) - viewport.h);
-            y2 = (float)((rand() % (viewport.h * 2)) - viewport.h);
+            x1 = (float)((SDL_rand() % (viewport.w * 2)) - viewport.w);
+            x2 = (float)((SDL_rand() % (viewport.w * 2)) - viewport.w);
+            y1 = (float)((SDL_rand() % (viewport.h * 2)) - viewport.h);
+            y2 = (float)((SDL_rand() % (viewport.h * 2)) - viewport.h);
             SDL_RenderLine(renderer, x1, y1, x2, y2);
         }
     }
@@ -168,10 +165,10 @@ static void DrawRects(SDL_Renderer *renderer)
         SDL_SetRenderDrawColor(renderer, 255, (Uint8)current_color,
                                (Uint8)current_color, (Uint8)current_alpha);
 
-        rect.w = (float)(rand() % (viewport.h / 2));
-        rect.h = (float)(rand() % (viewport.h / 2));
-        rect.x = (float)((rand() % (viewport.w * 2) - viewport.w) - (rect.w / 2));
-        rect.y = (float)((rand() % (viewport.h * 2) - viewport.h) - (rect.h / 2));
+        rect.w = (float)(SDL_rand() % (viewport.h / 2));
+        rect.h = (float)(SDL_rand() % (viewport.h / 2));
+        rect.x = (float)((SDL_rand() % (viewport.w * 2) - viewport.w) - (rect.w / 2));
+        rect.y = (float)((SDL_rand() % (viewport.h * 2) - viewport.h) - (rect.h / 2));
         SDL_RenderFillRect(renderer, &rect);
     }
 }
@@ -293,8 +290,6 @@ int main(int argc, char *argv[])
         SDL_RenderClear(renderer);
     }
 
-    srand((unsigned int)time(NULL));
-
     /* Main render loop */
     frames = 0;
     next_fps_check = SDL_GetTicks() + fps_check_delay;

test/testffmpeg.c

@@ -14,9 +14,6 @@
  * For a more complete video example, see ffplay.c in the ffmpeg sources.
  */
 
-#include <stdlib.h>
-#include <time.h>
-
 #include <SDL3/SDL.h>
 #include <SDL3/SDL_main.h>
 #include <SDL3/SDL_test.h>
@@ -1486,17 +1483,16 @@ int main(int argc, char *argv[])
     /* Position sprites and set their velocities */
     SDL_Rect viewport;
     SDL_GetRenderViewport(renderer, &viewport);
-    srand((unsigned int)time(NULL));
     for (i = 0; i < num_sprites; ++i) {
-        positions[i].x = (float)(rand() % (viewport.w - sprite_w));
-        positions[i].y = (float)(rand() % (viewport.h - sprite_h));
+        positions[i].x = (float)(SDL_rand() % (viewport.w - sprite_w));
+        positions[i].y = (float)(SDL_rand() % (viewport.h - sprite_h));
         positions[i].w = (float)sprite_w;
         positions[i].h = (float)sprite_h;
         velocities[i].x = 0.0f;
         velocities[i].y = 0.0f;
         while (velocities[i].x == 0.f || velocities[i].y == 0.f) {
-            velocities[i].x = (float)((rand() % (2 + 1)) - 1);
-            velocities[i].y = (float)((rand() % (2 + 1)) - 1);
+            velocities[i].x = (float)((SDL_rand() % (2 + 1)) - 1);
+            velocities[i].y = (float)((SDL_rand() % (2 + 1)) - 1);
         }
     }
 

test/testgeometry.c

@@ -12,6 +12,8 @@
 
 /* Simple program:  draw a RGB triangle, with texture  */
 
+#include <stdlib.h>
+
 #include "testutils.h"
 #include <SDL3/SDL.h>
 #include <SDL3/SDL_main.h>
@@ -21,9 +23,6 @@
 #include <emscripten/emscripten.h>
 #endif
 
-#include <stdlib.h>
-#include <time.h>
-
 static SDLTest_CommonState *state;
 static SDL_bool use_texture = SDL_FALSE;
 static SDL_Texture **sprites;
@@ -260,8 +259,6 @@ int main(int argc, char *argv[])
         }
     }
 
-    srand((unsigned int)time(NULL));
-
     /* Main render loop */
     frames = 0;
     then = SDL_GetTicks();

test/testintersections.c

@@ -19,9 +19,6 @@
 #include <emscripten/emscripten.h>
 #endif
 
-#include <stdlib.h>
-#include <time.h>
-
 #define SWAP(typ, a, b) \
     do {                \
         typ t = a;      \
@@ -77,8 +74,8 @@ static void DrawPoints(SDL_Renderer *renderer)
         SDL_SetRenderDrawColor(renderer, 255, (Uint8)current_color,
                                (Uint8)current_color, (Uint8)current_alpha);
 
-        x = (float)(rand() % viewport.w);
-        y = (float)(rand() % viewport.h);
+        x = (float)(SDL_rand() % viewport.w);
+        y = (float)(SDL_rand() % viewport.h);
         SDL_RenderPoint(renderer, x, y);
     }
 }
@@ -234,10 +231,10 @@ static void loop(void *arg)
                     num_lines = 0;
                 } else {
                     add_line(
-                        (float)(rand() % 640),
-                        (float)(rand() % 480),
-                        (float)(rand() % 640),
-                        (float)(rand() % 480));
+                        (float)(SDL_rand() % 640),
+                        (float)(SDL_rand() % 480),
+                        (float)(SDL_rand() % 640),
+                        (float)(SDL_rand() % 480));
                 }
                 break;
             case 'r':
@@ -245,10 +242,10 @@ static void loop(void *arg)
                     num_rects = 0;
                 } else {
                     add_rect(
-                        (float)(rand() % 640),
-                        (float)(rand() % 480),
-                        (float)(rand() % 640),
-                        (float)(rand() % 480));
+                        (float)(SDL_rand() % 640),
+                        (float)(SDL_rand() % 480),
+                        (float)(SDL_rand() % 640),
+                        (float)(SDL_rand() % 480));
                 }
                 break;
             default:
@@ -363,8 +360,6 @@ int main(int argc, char *argv[])
         SDL_RenderClear(renderer);
     }
 
-    srand((unsigned int)time(NULL));
-
     /* Main render loop */
     frames = 0;
     then = SDL_GetTicks();

test/testnative.c

@@ -11,6 +11,8 @@
 */
 /* Simple program:  Create a native window and attach an SDL renderer */
 
+#include <stdlib.h>
+
 #include <SDL3/SDL.h>
 #include <SDL3/SDL_main.h>
 #include <SDL3/SDL_test.h>
@@ -18,9 +20,6 @@
 #include "testnative.h"
 #include "testutils.h"
 
-#include <stdlib.h> /* for srand() */
-#include <time.h>   /* for time() */
-
 #define WINDOW_W    640
 #define WINDOW_H    480
 #define NUM_SPRITES 100
@@ -188,17 +187,16 @@ int main(int argc, char *argv[])
         SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Out of memory!\n");
         quit(2);
     }
-    srand((unsigned int)time(NULL));
     for (i = 0; i < NUM_SPRITES; ++i) {
-        positions[i].x = (float)(rand() % (window_w - (int)sprite_w));
-        positions[i].y = (float)(rand() % (window_h - (int)sprite_h));
+        positions[i].x = (float)(SDL_rand() % (window_w - (int)sprite_w));
+        positions[i].y = (float)(SDL_rand() % (window_h - (int)sprite_h));
         positions[i].w = sprite_w;
         positions[i].h = sprite_h;
         velocities[i].x = 0.0f;
         velocities[i].y = 0.0f;
         while (velocities[i].x == 0.f && velocities[i].y == 0.f) {
-            velocities[i].x = (float)((rand() % (MAX_SPEED * 2 + 1)) - MAX_SPEED);
-            velocities[i].y = (float)((rand() % (MAX_SPEED * 2 + 1)) - MAX_SPEED);
+            velocities[i].x = (float)((SDL_rand() % (MAX_SPEED * 2 + 1)) - MAX_SPEED);
+            velocities[i].y = (float)((SDL_rand() % (MAX_SPEED * 2 + 1)) - MAX_SPEED);
         }
     }
 

test/testoffscreen.c

@@ -21,9 +21,6 @@
 #include <emscripten/emscripten.h>
 #endif
 
-#include <stdlib.h>
-#include <time.h>
-
 static SDL_Renderer *renderer = NULL;
 static SDL_Window *window = NULL;
 static int done = SDL_FALSE;
@@ -137,8 +134,6 @@ int main(int argc, char *argv[])
 
     SDL_RenderClear(renderer);
 
-    srand((unsigned int)time(NULL));
-
 #ifndef SDL_PLATFORM_EMSCRIPTEN
     /* Main render loop */
     frames = 0;

test/testpopup.c

@@ -20,7 +20,6 @@ freely.
 #endif
 
 #include <stdlib.h>
-#include <time.h>
 
 #define MENU_WIDTH  120
 #define MENU_HEIGHT 300

test/testrelative.c

@@ -19,9 +19,6 @@
 #include <emscripten/emscripten.h>
 #endif
 
-#include <stdlib.h>
-#include <time.h>
-
 static SDLTest_CommonState *state;
 static int i, done;
 static float mouseX, mouseY;
@@ -115,7 +112,6 @@ int main(int argc, char *argv[])
         SDL_RenderClear(renderer);
     }
 
-    srand((unsigned int)time(NULL));
     if (SDL_SetRelativeMouseMode(SDL_TRUE) < 0) {
         return 3;
     }

test/testspriteminimal.c

@@ -18,9 +18,6 @@
 #include <emscripten/emscripten.h>
 #endif
 
-#include <stdlib.h>
-#include <time.h>
-
 #include "icon.h"
 
 #define WINDOW_WIDTH  640
@@ -136,17 +133,16 @@ int main(int argc, char *argv[])
     }
 
     /* Initialize the sprite positions */
-    srand((unsigned int)time(NULL));
     for (i = 0; i < NUM_SPRITES; ++i) {
-        positions[i].x = (float)(rand() % (WINDOW_WIDTH - sprite_w));
-        positions[i].y = (float)(rand() % (WINDOW_HEIGHT - sprite_h));
+        positions[i].x = (float)(SDL_rand() % (WINDOW_WIDTH - sprite_w));
+        positions[i].y = (float)(SDL_rand() % (WINDOW_HEIGHT - sprite_h));
         positions[i].w = (float)sprite_w;
         positions[i].h = (float)sprite_h;
         velocities[i].x = 0.0f;
         velocities[i].y = 0.0f;
         while (velocities[i].x == 0.f && velocities[i].y == 0.f) {
-            velocities[i].x = (float)((rand() % (MAX_SPEED * 2 + 1)) - MAX_SPEED);
-            velocities[i].y = (float)((rand() % (MAX_SPEED * 2 + 1)) - MAX_SPEED);
+            velocities[i].x = (float)((SDL_rand() % (MAX_SPEED * 2 + 1)) - MAX_SPEED);
+            velocities[i].y = (float)((SDL_rand() % (MAX_SPEED * 2 + 1)) - MAX_SPEED);
         }
     }
 

test/testwaylandcustom.c

@@ -10,9 +10,6 @@
   freely.
 */
 
-#include <stdlib.h>
-#include <time.h>
-
 #include <SDL3/SDL.h>
 #include <wayland-client.h>
 #include <xdg-shell-client-protocol.h>
@@ -99,17 +96,16 @@ static int InitSprites(void)
         return -1;
     }
 
-    srand((unsigned int)time(NULL));
     for (int i = 0; i < NUM_SPRITES; ++i) {
-        positions[i].x = (float)(rand() % (WINDOW_WIDTH - sprite_w));
-        positions[i].y = (float)(rand() % (WINDOW_HEIGHT - sprite_h));
+        positions[i].x = (float)(SDL_rand() % (WINDOW_WIDTH - sprite_w));
+        positions[i].y = (float)(SDL_rand() % (WINDOW_HEIGHT - sprite_h));
         positions[i].w = (float)sprite_w;
         positions[i].h = (float)sprite_h;
         velocities[i].x = 0.0f;
         velocities[i].y = 0.0f;
         while (velocities[i].x == 0.f && velocities[i].y == 0.f) {
-            velocities[i].x = (float)((rand() % (MAX_SPEED * 2 + 1)) - MAX_SPEED);
-            velocities[i].y = (float)((rand() % (MAX_SPEED * 2 + 1)) - MAX_SPEED);
+            velocities[i].x = (float)((SDL_rand() % (MAX_SPEED * 2 + 1)) - MAX_SPEED);
+            velocities[i].y = (float)((SDL_rand() % (MAX_SPEED * 2 + 1)) - MAX_SPEED);
         }
     }