initial commit, 4.5 stable

thirdparty/sdl/stdlib/SDL_memset.c

@@ -0,0 +1,139 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2025 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"
+
+
+#ifdef SDL_memset
+#undef SDL_memset
+#endif
+#if SDL_DYNAMIC_API
+#define SDL_memset SDL_memset_REAL
+#endif
+void *SDL_memset(SDL_OUT_BYTECAP(len) void *dst, int c, size_t len)
+{
+#if defined(__GNUC__) && (defined(HAVE_LIBC) && HAVE_LIBC)
+    return __builtin_memset(dst, c, len);
+#elif defined(HAVE_MEMSET)
+    return memset(dst, c, len);
+#else
+    size_t left;
+    Uint32 *dstp4;
+    Uint8 *dstp1 = (Uint8 *)dst;
+    Uint8 value1;
+    Uint32 value4;
+
+    // The value used in memset() is a byte, passed as an int
+    c &= 0xff;
+
+    /* The destination pointer needs to be aligned on a 4-byte boundary to
+     * execute a 32-bit set. Set first bytes manually if needed until it is
+     * aligned. */
+    value1 = (Uint8)c;
+    while ((uintptr_t)dstp1 & 0x3) {
+        if (len--) {
+            *dstp1++ = value1;
+        } else {
+            return dst;
+        }
+    }
+
+    value4 = ((Uint32)c | ((Uint32)c << 8) | ((Uint32)c << 16) | ((Uint32)c << 24));
+    dstp4 = (Uint32 *)dstp1;
+    left = (len % 4);
+    len /= 4;
+    while (len--) {
+        *dstp4++ = value4;
+    }
+
+    dstp1 = (Uint8 *)dstp4;
+    switch (left) {
+    case 3:
+        *dstp1++ = value1;
+        SDL_FALLTHROUGH;
+    case 2:
+        *dstp1++ = value1;
+        SDL_FALLTHROUGH;
+    case 1:
+        *dstp1++ = value1;
+    }
+
+    return dst;
+#endif // HAVE_MEMSET
+}
+
+// Note that memset() is a byte assignment and this is a 32-bit assignment, so they're not directly equivalent.
+void *SDL_memset4(void *dst, Uint32 val, size_t dwords)
+{
+#if defined(__APPLE__) && defined(HAVE_STRING_H)
+    memset_pattern4(dst, &val, dwords * 4);
+#elif defined(__GNUC__) && defined(__i386__)
+    int u0, u1, u2;
+    __asm__ __volatile__(
+        "cld \n\t"
+        "rep ; stosl \n\t"
+        : "=&D"(u0), "=&a"(u1), "=&c"(u2)
+        : "0"(dst), "1"(val), "2"(SDL_static_cast(Uint32, dwords))
+        : "memory");
+#else
+    size_t _n = (dwords + 3) / 4;
+    Uint32 *_p = SDL_static_cast(Uint32 *, dst);
+    Uint32 _val = (val);
+    if (dwords == 0) {
+        return dst;
+    }
+    switch (dwords % 4) {
+    case 0:
+        do {
+            *_p++ = _val;
+            SDL_FALLTHROUGH;
+        case 3:
+            *_p++ = _val;
+            SDL_FALLTHROUGH;
+        case 2:
+            *_p++ = _val;
+            SDL_FALLTHROUGH;
+        case 1:
+            *_p++ = _val;
+        } while (--_n);
+    }
+#endif
+    return dst;
+}
+
+/* The optimizer on Visual Studio 2005 and later generates memcpy() and memset() calls.
+   We will provide our own implementation if we're not building with a C runtime. */
+#ifndef HAVE_LIBC
+// NOLINTNEXTLINE(readability-redundant-declaration)
+extern void *memset(void *dst, int c, size_t len);
+#if defined(_MSC_VER) && !defined(__INTEL_LLVM_COMPILER)
+#pragma intrinsic(memset)
+#endif
+
+#if defined(_MSC_VER) && !defined(__clang__)
+#pragma function(memset)
+#endif
+// NOLINTNEXTLINE(readability-inconsistent-declaration-parameter-name)
+void *memset(void *dst, int c, size_t len)
+{
+    return SDL_memset(dst, c, len);
+}
+#endif // !HAVE_LIBC
+