diff options
Diffstat (limited to 'third_party/heimdal/lib/roken/clz.c')
-rw-r--r-- | third_party/heimdal/lib/roken/clz.c | 69 |
1 files changed, 69 insertions, 0 deletions
diff --git a/third_party/heimdal/lib/roken/clz.c b/third_party/heimdal/lib/roken/clz.c new file mode 100644 index 0000000..1a36234 --- /dev/null +++ b/third_party/heimdal/lib/roken/clz.c @@ -0,0 +1,69 @@ +/* + * Copyright (C) 2015 THL A29 Limited, a Tencent company, and Milo Yip. + * All rights reserved. + * + * Permission is hereby granted, free of charge, to any person obtaining a copy + * of this software and associated documentation files (the "Software"), to deal + * in the Software without restriction, including without limitation the rights + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell + * copies of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN + * THE SOFTWARE. + */ + +#include <config.h> +#include <assert.h> + +#include "roken.h" + +#if defined(_MSC_VER) +#include <intrin.h> +#if defined(_WIN64) +#pragma intrinsic(_BitScanReverse64) +#else +#pragma intrinsic(_BitScanReverse) +#endif +#endif + +ROKEN_LIB_FUNCTION int ROKEN_LIB_CALL +rk_clzll(uint64_t x) +{ +#if defined(_MSC_VER) + unsigned long r = 0; +#elif !(defined(__GNUC__) && __GNUC__ >= 4) + int r = 0; +#endif + + assert(x != 0); + +#if defined(_MSC_VER) +# if defined(_WIN64) + _BitScanReverse64(&r, x); +# else + if (_BitScanReverse(&r, (uint32_t)(x >> 32))) + return 63 - (r + 32); + _BitScanReverse(&r, (uint32_t)(x & 0xFFFFFFFF)); +# endif + + return 63 - r; +#elif (defined(__GNUC__) && __GNUC__ >= 4) + return __builtin_clzll(x); +#else + while (!(x & ((uint64_t)1 << 63))) { + x <<= 1; + ++r; + } + + return r; +#endif /* _MSC_VER || __GNUC__ */ +} |