| /* |
| * This file is part of the coreboot project. |
| * |
| * Copyright 2015 Google Inc. |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License as published by |
| * the Free Software Foundation; version 2 of the License. |
| * |
| * This program is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| * GNU General Public License for more details. |
| */ |
| |
| #include <types.h> |
| |
| /* |
| * Provide platform-independent backend implementation for __builtin_clz() in |
| * <lib.h> in case GCC does not have an assembly version for this arch. |
| */ |
| |
| #if !IS_ENABLED(CONFIG_ARCH_X86) /* work around lack of --gc-sections on x86 */ |
| int __clzsi2(u32 a); |
| int __clzsi2(u32 a) |
| { |
| static const u8 four_bit_table[] = { |
| [0x0] = 4, [0x1] = 3, [0x2] = 2, [0x3] = 2, |
| [0x4] = 1, [0x5] = 1, [0x6] = 1, [0x7] = 1, |
| [0x8] = 0, [0x9] = 0, [0xa] = 0, [0xb] = 0, |
| [0xc] = 0, [0xd] = 0, [0xe] = 0, [0xf] = 0, |
| }; |
| int r = 0; |
| |
| if (!(a & (0xffffU << 16))) { |
| r += 16; |
| a <<= 16; |
| } |
| |
| if (!(a & (0xffU << 24))) { |
| r += 8; |
| a <<= 8; |
| } |
| |
| if (!(a & (0xfU << 28))) { |
| r += 4; |
| a <<= 4; |
| } |
| |
| return r + four_bit_table[a >> 28]; |
| } |
| #endif |