util.h

00001 /*Copyright (C) 2008-2009  Timothy B. Terriberry (tterribe@xiph.org)
00002   You can redistribute this library and/or modify it under the terms of the
00003    GNU Lesser General Public License as published by the Free Software
00004    Foundation; either version 2.1 of the License, or (at your option) any later
00005    version.*/
00006 #if !defined(_qrcode_util_H)
00007 # define _qrcode_util_H (1)
00008 
00009 #define QR_MAXI(_a,_b)      ((_a)-((_a)-(_b)&-((_b)>(_a))))
00010 #define QR_MINI(_a,_b)      ((_a)+((_b)-(_a)&-((_b)<(_a))))
00011 #define QR_SIGNI(_x)        (((_x)>0)-((_x)<0))
00012 #define QR_SIGNMASK(_x)     (-((_x)<0))
00013 /*Unlike copysign(), simply inverts the sign of _a if _b is negative.*/
00014 #define QR_FLIPSIGNI(_a,_b) ((_a)+QR_SIGNMASK(_b)^QR_SIGNMASK(_b))
00015 #define QR_COPYSIGNI(_a,_b) QR_FLIPSIGNI(abs(_a),_b)
00016 /*Divides a signed integer by a positive value with exact rounding.*/
00017 #define QR_DIVROUND(_x,_y)  (((_x)+QR_FLIPSIGNI(_y>>1,_x))/(_y))
00018 #define QR_CLAMPI(_a,_b,_c) (QR_MAXI(_a,QR_MINI(_b,_c)))
00019 #define QR_CLAMP255(_x)     ((unsigned char)((((_x)<0)-1)&((_x)|-((_x)>255))))
00020 /*Swaps two integers _a and _b if _a>_b.*/
00021 #define QR_SORT2I(_a,_b) \
00022   do{ \
00023     int t__; \
00024     t__=QR_MINI(_a,_b)^(_a); \
00025     (_a)^=t__; \
00026     (_b)^=t__; \
00027   } \
00028   while(0)
00029 #define QR_ILOG0(_v) (!!((_v)&0x2))
00030 #define QR_ILOG1(_v) (((_v)&0xC)?2+QR_ILOG0((_v)>>2):QR_ILOG0(_v))
00031 #define QR_ILOG2(_v) (((_v)&0xF0)?4+QR_ILOG1((_v)>>4):QR_ILOG1(_v))
00032 #define QR_ILOG3(_v) (((_v)&0xFF00)?8+QR_ILOG2((_v)>>8):QR_ILOG2(_v))
00033 #define QR_ILOG4(_v) (((_v)&0xFFFF0000)?16+QR_ILOG3((_v)>>16):QR_ILOG3(_v))
00034 /*Computes the integer logarithm of a (positive, 32-bit) constant.*/
00035 #define QR_ILOG(_v) ((int)QR_ILOG4((unsigned)(_v)))
00036 
00037 /*Multiplies 32-bit numbers _a and _b, adds (possibly 64-bit) number _r, and
00038    takes bits [_s,_s+31] of the result.*/
00039 #define QR_FIXMUL(_a,_b,_r,_s) ((int)((_a)*(long long)(_b)+(_r)>>(_s)))
00040 /*Multiplies 32-bit numbers _a and _b, adds (possibly 64-bit) number _r, and
00041    gives all 64 bits of the result.*/
00042 #define QR_EXTMUL(_a,_b,_r)    ((_a)*(long long)(_b)+(_r))
00043 
00044 unsigned qr_isqrt(unsigned _val);
00045 unsigned qr_ihypot(int _x,int _y);
00046 int qr_ilog(unsigned _val);
00047 
00048 #endif
00049