SFBMath.h

00001 /*                                              -*- mode:C++; fill-column:100 -*-
00002   SFBMath.h - Misc bit twiddling and mathy routines, just in case
00003   Copyright (C) 2009 The Regents of the University of New Mexico.  All rights reserved.
00004 
00005   This library is free software; you can redistribute it and/or
00006   modify it under the terms of the GNU Lesser General Public
00007   License as published by the Free Software Foundation; either
00008   version 2.1 of the License, or (at your option) any later version.
00009 
00010   This library is distributed in the hope that it will be useful,
00011   but WITHOUT ANY WARRANTY; without even the implied warranty of
00012   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00013   Lesser General Public License for more details.
00014 
00015   You should have received a copy of the GNU General Public License
00016   along with this library; if not, write to the Free Software
00017   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301
00018   USA
00019 
00020   $Id$
00021 */
00022 
00023 #ifndef SFBMATH_H
00024 #define SFBMATH_H
00025 
00026 #include "SFBTypes.h"
00027 
00028 #ifdef __cplusplus
00029 extern "C" {
00030 #endif
00031 
00032 #if defined(HOST_MODE) || defined(__thumb__)
00033 
00037 #define COUNT_LEADING_ZEROS(u32InputVal, u32OutputCount)              \
00038  do {                                                                 \
00039   (u32InputVal) |= (u32InputVal)>>1;                                  \
00040   (u32InputVal) |= (u32InputVal)>>2;                                  \
00041   (u32InputVal) |= (u32InputVal)>>2;                                  \
00042   (u32InputVal) |= (u32InputVal)>>4;                                  \
00043   (u32InputVal) |= (u32InputVal)>>8;                                  \
00044   (u32InputVal) |= (u32InputVal)>>16;                                 \
00045   (u32OutputCount) = 32-countOnes(u32InputVal);                       \
00046  } while (0)
00047 
00048 #else
00049 
00054 #define COUNT_LEADING_ZEROS(u32InputVal, u32OutputCount)              \
00055  /* 16 cycle leading zero count algorithm */                          \
00056   __asm__ __volatile__ ("movs   %[count],%[val],lsr #16\n\t"          \
00057                         "mov    %[count],#0\n\t"                      \
00058                         "addeq  %[count],%[count],#16\n\t"            \
00059                         "moveqs %[val],%[val],lsl #16\n\t"            \
00060                         "addeq  %[count],%[count],#1\n\t"             \
00061                         "tst    %[val],#0xff000000\n\t"               \
00062                         "addeq  %[count],%[count],#8\n\t"             \
00063                         "moveq  %[val],%[val],lsl #8\n\t"             \
00064                         "tst    %[val],#0xf0000000\n\t"               \
00065                         "addeq  %[count],%[count],#4\n\t"             \
00066                         "moveq  %[val],%[val],lsl #4\n\t"             \
00067                         "tst    %[val],#0xc0000000\n\t"               \
00068                         "addeq  %[count],%[count],#2\n\t"             \
00069                         "moveq  %[val],%[val],lsl #2\n\t"             \
00070                         "tst    %[val],#0x80000000\n\t"               \
00071                         "addeq  %[count],%[count],#1"                 \
00072                         : [count] "=r" (u32OutputCount),              \
00073                           [val] "+r" (u32InputVal)                    \
00074                         : )
00075 #endif
00076 
00077 extern int countLeadingZeros(u32 x) ;
00078 
00079 extern int countOnes(u32 x) ;
00080 
00081 extern int countTrailingZeros(int x) ;
00082 
00083 #ifdef __cplusplus
00084 }
00085 #endif
00086 
00087 
00088 #endif /* SFBMATH_H */
00089