Added SDL_murmur3_32()

src/dynapi/SDL_dynapi.sym

@@ -1097,6 +1097,7 @@ SDL3_0.0.0 {
     SDL_memset;
     SDL_modf;
     SDL_modff;
+    SDL_murmur3_32;
     SDL_pow;
     SDL_powf;
     SDL_qsort;

src/dynapi/SDL_dynapi_overrides.h

@@ -1122,6 +1122,7 @@
 #define SDL_memset4 SDL_memset4_REAL
 #define SDL_modf SDL_modf_REAL
 #define SDL_modff SDL_modff_REAL
+#define SDL_murmur3_32 SDL_murmur3_32_REAL
 #define SDL_pow SDL_pow_REAL
 #define SDL_powf SDL_powf_REAL
 #define SDL_qsort SDL_qsort_REAL

src/dynapi/SDL_dynapi_procs.h

@@ -1131,6 +1131,7 @@ SDL_DYNAPI_PROC(void*,SDL_memset,(SDL_OUT_BYTECAP(c) void *a, int b, size_t c),(
 SDL_DYNAPI_PROC(void*,SDL_memset4,(void *a, Uint32 b, size_t c),(a,b,c),return)
 SDL_DYNAPI_PROC(double,SDL_modf,(double a, double *b),(a,b),return)
 SDL_DYNAPI_PROC(float,SDL_modff,(float a, float *b),(a,b),return)
+SDL_DYNAPI_PROC(Uint32,SDL_murmur3_32,(const void *a, size_t b, Uint32 c),(a,b,c),return)
 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),)

src/stdlib/SDL_murmur3.c

@@ -0,0 +1,87 @@
+/*
+  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"
+
+// Public domain murmur3 32-bit hash algorithm
+//
+// Adapted from: https://en.wikipedia.org/wiki/MurmurHash
+
+static SDL_INLINE Uint32 murmur_32_scramble(Uint32 k)
+{
+    k *= 0xcc9e2d51;
+    k = (k << 15) | (k >> 17);
+    k *= 0x1b873593;
+    return k;
+}
+
+Uint32 SDLCALL SDL_murmur3_32(const void *data, size_t len, Uint32 seed)
+{
+    const Uint8 *bytes = (const Uint8 *)data;
+    Uint32 hash = seed;
+    Uint32 k;
+
+    // Read in groups of 4.
+    if ((((uintptr_t)bytes) & 3) == 0) {
+        // We can do aligned 32-bit reads
+        for (size_t i = len >> 2; i--; ) {
+            k = *(const Uint32 *)bytes;
+            k = SDL_Swap32LE(k);
+            bytes += sizeof(Uint32);
+            hash ^= murmur_32_scramble(k);
+            hash = (hash << 13) | (hash >> 19);
+            hash = hash * 5 + 0xe6546b64;
+        }
+    } else {
+        for (size_t i = len >> 2; i--; ) {
+            SDL_memcpy(&k, bytes, sizeof(Uint32));
+            k = SDL_Swap32LE(k);
+            bytes += sizeof(Uint32);
+            hash ^= murmur_32_scramble(k);
+            hash = (hash << 13) | (hash >> 19);
+            hash = hash * 5 + 0xe6546b64;
+        }
+    }
+
+    // Read the rest.
+    size_t left = (len & 3);
+    if (left) {
+        k = 0;
+        for (size_t i = left; i--; ) {
+            k <<= 8;
+            k |= bytes[i];
+        }
+
+        // A swap is *not* necessary here because the preceding loop already
+        // places the low bytes in the low places according to whatever endianness
+        // we use. Swaps only apply when the memory is copied in a chunk.
+        hash ^= murmur_32_scramble(k);
+    }
+
+    /* Finalize. */
+    hash ^= len;
+    hash ^= hash >> 16;
+    hash *= 0x85ebca6b;
+    hash ^= hash >> 13;
+    hash *= 0xc2b2ae35;
+    hash ^= hash >> 16;
+
+    return hash;
+}