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ae7446a959
This is done such that we can disable LTO for these 2 functions when building with MSVC. This is due to a limitation of Link Time Code Generation (LTCG). Code generation might generate a new reference to memset after linking has started. The LTCG must make assumptions about where memset is defined which is normally the C runtime.
76 lines
2.1 KiB
C
76 lines
2.1 KiB
C
/*
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Simple DirectMedia Layer
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Copyright (C) 1997-2022 Sam Lantinga <slouken@libsdl.org>
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This software is provided 'as-is', without any express or implied
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warranty. In no event will the authors be held liable for any damages
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arising from the use of this software.
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Permission is granted to anyone to use this software for any purpose,
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including commercial applications, and to alter it and redistribute it
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freely, subject to the following restrictions:
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1. The origin of this software must not be misrepresented; you must not
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claim that you wrote the original software. If you use this software
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in a product, an acknowledgment in the product documentation would be
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appreciated but is not required.
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2. Altered source versions must be plainly marked as such, and must not be
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misrepresented as being the original software.
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3. This notice may not be removed or altered from any source distribution.
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*/
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#include "../SDL_internal.h"
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/* This file contains a portable memset manipulation function for SDL */
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void *
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SDL_memset(SDL_OUT_BYTECAP(len) void *dst, int c, size_t len)
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{
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#if defined(HAVE_MEMSET)
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return memset(dst, c, len);
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#else
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size_t left;
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Uint32 *dstp4;
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Uint8 *dstp1 = (Uint8 *) dst;
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Uint8 value1;
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Uint32 value4;
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/* The value used in memset() is a byte, passed as an int */
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c &= 0xff;
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/* The destination pointer needs to be aligned on a 4-byte boundary to
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* execute a 32-bit set. Set first bytes manually if needed until it is
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* aligned. */
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value1 = (Uint8)c;
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while ((uintptr_t)dstp1 & 0x3) {
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if (len--) {
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*dstp1++ = value1;
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} else {
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return dst;
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}
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}
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value4 = ((Uint32)c | ((Uint32)c << 8) | ((Uint32)c << 16) | ((Uint32)c << 24));
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dstp4 = (Uint32 *) dstp1;
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left = (len % 4);
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len /= 4;
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while (len--) {
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*dstp4++ = value4;
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}
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dstp1 = (Uint8 *) dstp4;
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switch (left) {
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case 3:
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*dstp1++ = value1;
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case 2:
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*dstp1++ = value1;
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case 1:
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*dstp1++ = value1;
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}
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return dst;
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#endif /* HAVE_MEMSET */
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}
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/* vi: set ts=4 sw=4 expandtab: */
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