From 5a079a2d114f96d4847d1ee305d5b7c16eeec50e Mon Sep 17 00:00:00 2001 From: 3gg <3gg@shellblade.net> Date: Sat, 27 Dec 2025 12:03:39 -0800 Subject: Initial commit --- contrib/SDL-3.2.8/src/stdlib/SDL_crc32.c | 50 ++++++++++++++++++++++++++++++++ 1 file changed, 50 insertions(+) create mode 100644 contrib/SDL-3.2.8/src/stdlib/SDL_crc32.c (limited to 'contrib/SDL-3.2.8/src/stdlib/SDL_crc32.c') diff --git a/contrib/SDL-3.2.8/src/stdlib/SDL_crc32.c b/contrib/SDL-3.2.8/src/stdlib/SDL_crc32.c new file mode 100644 index 0000000..9c2d097 --- /dev/null +++ b/contrib/SDL-3.2.8/src/stdlib/SDL_crc32.c @@ -0,0 +1,50 @@ +/* + Simple DirectMedia Layer + Copyright (C) 1997-2025 Sam Lantinga + + 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 CRC implementation adapted from: + http://home.thep.lu.se/~bjorn/crc/crc32_simple.c + + This algorithm is compatible with the 32-bit CRC described here: + https://www.lammertbies.nl/comm/info/crc-calculation +*/ +/* NOTE: DO NOT CHANGE THIS ALGORITHM + There is code that relies on this in the joystick code +*/ + +static Uint32 crc32_for_byte(Uint32 r) +{ + int i; + for (i = 0; i < 8; ++i) { + r = (r & 1 ? 0 : (Uint32)0xEDB88320L) ^ r >> 1; + } + return r ^ (Uint32)0xFF000000L; +} + +Uint32 SDL_crc32(Uint32 crc, const void *data, size_t len) +{ + // As an optimization we can precalculate a 256 entry table for each byte + size_t i; + for (i = 0; i < len; ++i) { + crc = crc32_for_byte((Uint8)crc ^ ((const Uint8 *)data)[i]) ^ crc >> 8; + } + return crc; +} -- cgit v1.2.3