double pow(double base, double exponent)

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bitshifter

Joined: 04 Dec 2007
Posts: 796
Location: Massachusetts, USA

bitshifter 25 Jul 2009, 03:48

Hello
I am writing graphics engine for my OS.
As i need certain std stuff along the way.
Writing an integer pow is easy but for doubles?

C Prototype from math library is like...

Quote:

double pow(double base, double exponent)

I am creating gammatized palette on the fly.
So far its still in C but it is used like so...

Code:

unsigned char GetGammaLevel(double factor, int sellevels, int pallevels, int index)
{
   double intensity;
   double power;
   unsigned char result;

   result = 0;
   sellevels--;
   pallevels--;

   if(index > 0)
   {
      intensity = (double)index / (double)sellevels;
      power = pow(intensity, 1.0 / factor);
      result = (unsigned char)((power * pallevels) + 0.5);
   }

   return result;
}

void InitPalette(unsigned char palette[768])
{
   int red;
   int green;
   int blue;
   int index;
   int index2;
   unsigned char level;

   for(red = 0; red < 4; red++)
   {
      for(green = 0; green < 4; green++)
      {
         for(blue = 0; blue < 4; blue++)
         {
            index = ((red << 4) + (green << 2) + blue) * 3;

            palette[index]   = GetGammaLevel(2.3,4,64,red);
            palette[index+1] = GetGammaLevel(2.3,4,64,green);
            palette[index+2] = GetGammaLevel(2.3,4,64,blue);
         }
      }
   }

   for(index = 0; index < 64; index++)
   {
      level = GetGammaLevel(2.3,64,64,index);

      index2 = (index + 64) * 3;
      palette[index2] = level;
      palette[index2+1] = 0;
      palette[index2+2] = 0;

      index2 = (index + 128) * 3;
      palette[index2] = 0;
      palette[index2+1] = level;
      palette[index2+2] = 0;

      index2 = (index + 192) * 3;
      palette[index2] = 0;
      palette[index2+1] = 0;
      palette[index2+2] = level;
   }
}

I have all this C code from my engine i have to port.
If you feel like helping out i would be very happy.

_________________
Coding a 3D game engine with fasm is like trying to eat an elephant,
you just have to keep focused and take it one 'byte' at a time.

25 Jul 2009, 03:48

asmcoder

Joined: 02 Jun 2008
Posts: 784

asmcoder 25 Jul 2009, 13:55

[content deleted]

Last edited by asmcoder on 14 Aug 2009, 14:48; edited 1 time in total

25 Jul 2009, 13:55

bitshifter

Joined: 04 Dec 2007
Posts: 796
Location: Massachusetts, USA

bitshifter 25 Jul 2009, 14:38

I wish it were that simple.
After searching the net for days i have found 1 example in masm.
Now if i can just figure out how it really works Confused

I just got olly so im gonna go see how MS-VC6 does it.
These things always turn out way more complex than i forsee.

25 Jul 2009, 14:38

Fanael

Joined: 03 Jul 2009
Posts: 168

Fanael 25 Jul 2009, 14:44

pow(x, y) = exp(ln(x) * y)

25 Jul 2009, 14:44

asmcoder

Joined: 02 Jun 2008
Posts: 784

asmcoder 25 Jul 2009, 14:51

[content deleted]

Last edited by asmcoder on 14 Aug 2009, 14:48; edited 1 time in total

25 Jul 2009, 14:51

Borsuc

Joined: 29 Dec 2005
Posts: 2465
Location: Bucharest, Romania

Borsuc 25 Jul 2009, 14:55

asmcoder this is about floating point, not integers. It can be much FASTER because you already have the exponent stored along with the mantissa, so the base 2 logarithm is extremely fast (there's even an instruction for that IIRC) you just take the exponent.

See Fanael's formula.

see this for instance:

http://www.website.masmforum.com/tutorials/fptute/fpuchap11.htm

25 Jul 2009, 14:55

LocoDelAssembly
Your code has a bug

Joined: 06 May 2005
Posts: 4624
Location: Argentina

LocoDelAssembly 25 Jul 2009, 18:02

Quote:

did you had in school long multiplication?

Did you had in school non natural exponents? You know, things like 3^(-2.5), for instance.

25 Jul 2009, 18:02

asmcoder

Joined: 02 Jun 2008
Posts: 784

asmcoder 25 Jul 2009, 18:28

[content deleted]

Last edited by asmcoder on 14 Aug 2009, 14:48; edited 1 time in total

25 Jul 2009, 18:28

madmatt

Joined: 07 Oct 2003
Posts: 1045
Location: Michigan, USA

madmatt 25 Jul 2009, 19:07

Hello bitshifter,
If you need a pow() function you can use the one in the msvcrt.dll which, I believe, is included with every windows OS version since 2000. I've posted the api defines below. You'll have to use 'cinvoke' macro to call it in fasm, and use the 'double' keyword to push double-floats onto the stack. Some Examples:

Code:

locals dfloat:QWORD, dvara:QWORD, dvarb:QWORD

cinvoke pow, double 5.0, double 2.0
fstp     [dfloat]

cinvoke pow, double [dvara], double [dvarb]
fstp     [dfloat]

Code:

import msvcrt,\
       _CIacos,'_CIacos',\
       _CIasin,'_CIasin',\
       _CIatan,'_CIatan',\
       _CIatan2,'_CIatan2',\
       _CIcos,'_CIcos',\
       _CIcosh,'_CIcosh',\
       _CIexp,'_CIexp',\
       _CIfmod,'_CIfmod',\
       _CIlog,'_CIlog',\
       _CIlog10,'_CIlog10',\
       _CIpow,'_CIpow',\
       _CIsin,'_CIsin',\
       _CIsinh,'_CIsinh',\
       _CIsqrt,'_CIsqrt',\
       _CItan,'_CItan',\
       _CItanh,'_CItanh',\
       _CxxThrowException,'_CxxThrowException',\
       _EH_prolog,'_EH_prolog',\
       _Getdays,'_Getdays',\
       _Getmonths,'_Getmonths',\
       _Gettnames,'_Gettnames',\
       _HUGE,'_HUGE',\
       _Strftime,'_Strftime',\
       _XcptFilter,'_XcptFilter',\
       __CxxCallUnwindDtor,'__CxxCallUnwindDtor',\
       __CxxDetectRethrow,'__CxxDetectRethrow',\
       __CxxExceptionFilter,'__CxxExceptionFilter',\
       __CxxFrameHandler,'__CxxFrameHandler',\
       __CxxLongjmpUnwind,'__CxxLongjmpUnwind',\
       __CxxQueryExceptionSize,'__CxxQueryExceptionSize',\
       __CxxRegisterExceptionObject,'__CxxRegisterExceptionObject',\
       __CxxUnregisterExceptionObject,'__CxxUnregisterExceptionObject',\
       __DestructExceptionObject,'__DestructExceptionObject',\
       __RTCastToVoid,'__RTCastToVoid',\
       __RTDynamicCast,'__RTDynamicCast',\
       __RTtypeid,'__RTtypeid',\
       __STRINGTOLD,'__STRINGTOLD',\
       ___lc_codepage_func,'___lc_codepage_func',\
       ___lc_handle_func,'___lc_handle_func',\
       ___mb_cur_max_func,'___mb_cur_max_func',\
       ___setlc_active_func,'___setlc_active_func',\
       ___unguarded_readlc_active_add_func,'___unguarded_readlc_active_add_func',\
       __argc,'__argc',\
       __argv,'__argv',\
       __badioinfo,'__badioinfo',\
       __crtCompareString ,'__crtCompareStringA',\
       __crtLCMapString ,'__crtLCMapStringA',\
       __dllonexit,'__dllonexit',\
       __doserrno,'__doserrno',\
       __fpecode,'__fpecode',\
       __getmainargs,'__getmainargs',\
       __initenv,'__initenv',\
       __iob_func,'__iob_func',\
       __isascii,'__isascii',\
       __iscsym,'__iscsym',\
       __iscsymf,'__iscsymf',\
       __lc_codepage,'__lc_codepage',\
       __lc_collate_cp,'__lc_collate_cp',\
       __lc_handle,'__lc_handle',\
       __lconv_init,'__lconv_init',\
       __mb_cur_max,'__mb_cur_max',\
       __p___argc,'__p___argc',\
       __p___argv,'__p___argv',\
       __p___initenv,'__p___initenv',\
       __p___mb_cur_max,'__p___mb_cur_max',\
       __p___wargv,'__p___wargv',\
       __p___winitenv,'__p___winitenv',\
       __p__acmdln,'__p__acmdln',\
       __p__amblksiz,'__p__amblksiz',\
       __p__commode,'__p__commode',\
       __p__daylight,'__p__daylight',\
       __p__dstbias,'__p__dstbias',\
       __p__environ,'__p__environ',\
       __p__fileinfo,'__p__fileinfo',\
       __p__fmode,'__p__fmode',\
       __p__iob,'__p__iob',\
       __p__mbcasemap,'__p__mbcasemap',\
       __p__mbctype,'__p__mbctype',\
       __p__osver,'__p__osver',\
       __p__pctype,'__p__pctype',\
       __p__pgmptr,'__p__pgmptr',\
       __p__pwctype,'__p__pwctype',\
       __p__timezone,'__p__timezone',\
       __p__tzname,'__p__tzname',\
       __p__wcmdln,'__p__wcmdln',\
       __p__wenviron,'__p__wenviron',\
       __p__winmajor,'__p__winmajor',\
       __p__winminor,'__p__winminor',\
       __p__winver,'__p__winver',\
       __p__wpgmptr,'__p__wpgmptr',\
       __pctype_func,'__pctype_func',\
       __pioinfo,'__pioinfo',\
       __pxcptinfoptrs,'__pxcptinfoptrs',\
       __set_app_type,'__set_app_type',\
       __setlc_active,'__setlc_active',\
       __setusermatherr,'__setusermatherr',\
       __threadhandle,'__threadhandle',\
       __threadid,'__threadid',\
       __toascii,'__toascii',\
       __unDName,'__unDName',\
       __unDNameEx,'__unDNameEx',\
       __uncaught_exception,'__uncaught_exception',\
       __unguarded_readlc_active,'__unguarded_readlc_active',\
       __wargv,'__wargv',\
       __wcserror,'__wcserror',\
       __wgetmainargs,'__wgetmainargs',\
       __winitenv,'__winitenv',\
       _abnormal_termination,'_abnormal_termination',\
       _access,'_access',\
       _acmdln,'_acmdln',\
       _adj_fdiv_m16i,'_adj_fdiv_m16i',\
       _adj_fdiv_m32,'_adj_fdiv_m32',\
       _adj_fdiv_m32i,'_adj_fdiv_m32i',\
       _adj_fdiv_m64,'_adj_fdiv_m64',\
       _adj_fdiv_r,'_adj_fdiv_r',\
       _adj_fdivr_m16i,'_adj_fdivr_m16i',\
       _adj_fdivr_m32,'_adj_fdivr_m32',\
       _adj_fdivr_m32i,'_adj_fdivr_m32i',\
       _adj_fdivr_m64,'_adj_fdivr_m64',\
       _adj_fpatan,'_adj_fpatan',\
       _adj_fprem,'_adj_fprem',\
       _adj_fprem1,'_adj_fprem1',\
       _adj_fptan,'_adj_fptan',\
       _adjust_fdiv,'_adjust_fdiv',\
       _aexit_rtn,'_aexit_rtn',\
       _aligned_free,'_aligned_free',\
       _aligned_malloc,'_aligned_malloc',\
       _aligned_offset_malloc,'_aligned_offset_malloc',\
       _aligned_offset_realloc,'_aligned_offset_realloc',\
       _aligned_realloc,'_aligned_realloc',\
       _amsg_exit,'_amsg_exit',\
       _assert,'_assert',\
       _atodbl,'_atodbl',\
       _atoi64,'_atoi64',\
       _atoldbl,'_atoldbl',\
       _beep,'_beep',\
       _beginthread,'_beginthread',\
       _beginthreadex,'_beginthreadex',\
       _c_exit,'_c_exit',\
       _cabs,'_cabs',\
       _callnewh,'_callnewh',\
       _cexit,'_cexit',\
       _cgets,'_cgets',\
       _cgetws,'_cgetws',\
       _chdir,'_chdir',\
       _chdrive,'_chdrive',\
       _chgsign,'_chgsign',\
       _chkesp,'_chkesp',\
       _chmod,'_chmod',\
       _chsize,'_chsize',\
       _clearfp,'_clearfp',\
       _close,'_close',\
       _commit,'_commit',\
       _commode,'_commode',\
       _control87,'_control87',\
       _controlfp,'_controlfp',\
       _copysign,'_copysign',\
       _cprintf,'_cprintf',\
       _cputs,'_cputs',\
       _cputws,'_cputws',\
       _creat,'_creat',\
       _cscanf,'_cscanf',\
       _ctime64,'_ctime64',\
       _ctype,'_ctype',\
       _cwait,'_cwait',\
       _cwprintf,'_cwprintf',\
       _cwscanf,'_cwscanf',\
       _daylight,'_daylight',\
       _dstbias,'_dstbias',\
       _dup,'_dup',\
       _dup2,'_dup2',\
       _ecvt,'_ecvt',\
       _endthread,'_endthread',\
       _endthreadex,'_endthreadex',\
       _environ,'_environ',\
       _eof,'_eof',\
       _errno,'_errno',\
       _except_handler2,'_except_handler2',\
       _except_handler3,'_except_handler3',\
       _execl,'_execl',\
       _execle,'_execle',\
       _execlp,'_execlp',\
       _execlpe,'_execlpe',\
       _execv,'_execv',\
       _execve,'_execve',\
       _execvp,'_execvp',\
       _execvpe,'_execvpe',\
       _exit,'_exit',\
       _expand,'_expand',\
       _fcloseall,'_fcloseall',\
       _fcvt,'_fcvt',\
       _fdopen,'_fdopen',\
       _fgetchar,'_fgetchar',\
       _fgetwchar,'_fgetwchar',\
       _filbuf,'_filbuf',\
       _fileinfo,'_fileinfo',\
       _filelength,'_filelength',\
       _filelengthi64,'_filelengthi64',\
       _fileno,'_fileno',\
       _findclose,'_findclose',\
       _findfirst,'_findfirst',\
       _findfirst64,'_findfirst64',\
       _findfirsti64,'_findfirsti64',\
       _findnext,'_findnext',\
       _findnext64,'_findnext64',\
       _findnexti64,'_findnexti64',\
       _finite,'_finite',\
       _flsbuf,'_flsbuf',\
       _flushall,'_flushall',\
       _fmode,'_fmode',\
       _fpclass,'_fpclass',\
       _fpieee_flt,'_fpieee_flt',\
       _fpreset,'_fpreset',\
       _fputchar,'_fputchar',\
       _fputwchar,'_fputwchar',\
       _fsopen,'_fsopen',\
       _fstat,'_fstat',\
       _fstat64,'_fstat64',\
       _fstati64,'_fstati64',\
       _ftime,'_ftime',\
       _ftime64,'_ftime64',\
       _ftol,'_ftol',\
       _fullpath,'_fullpath',\
       _futime,'_futime',\
       _futime64,'_futime64',\
       _gcvt,'_gcvt',\
       _get_heap_handle,'_get_heap_handle',\
       _get_osfhandle,'_get_osfhandle',\
       _get_sbh_threshold,'_get_sbh_threshold',\
       _getch,'_getch',\
       _getche,'_getche',\
       _getcwd,'_getcwd',\
       _getdcwd,'_getdcwd',\
       _getdiskfree,'_getdiskfree',\
       _getdllprocaddr,'_getdllprocaddr',\
       _getdrive,'_getdrive',\
       _getdrives,'_getdrives',\
       _getmaxstdio,'_getmaxstdio',\
       _getmbcp,'_getmbcp',\
       _getpid,'_getpid',\
       _getsystime,'_getsystime',\
       _getw,'_getw',\
       _getwch,'_getwch',\
       _getwche,'_getwche',\
       _getws,'_getws',\
       _global_unwind2,'_global_unwind2',\
       _gmtime64,'_gmtime64',\
       _heapadd,'_heapadd',\
       _heapchk,'_heapchk',\
       _heapmin,'_heapmin',\
       _heapset,'_heapset',\
       _heapused,'_heapused',\
       _heapwalk,'_heapwalk',\
       _hypot,'_hypot',\
       _i64toa,'_i64toa',\
       _i64tow,'_i64tow',\
       _initterm,'_initterm',\
       _inp,'_inp',\
       _inpd,'_inpd',\
       _inpw,'_inpw',\
       _iob,'_iob',\
       _isatty,'_isatty',\
       _isctype,'_isctype',\
       _ismbbalnum,'_ismbbalnum',\
       _ismbbalpha,'_ismbbalpha',\
       _ismbbgraph,'_ismbbgraph',\
       _ismbbkalnum,'_ismbbkalnum',\
       _ismbbkana,'_ismbbkana',\
       _ismbbkprint,'_ismbbkprint',\
       _ismbbkpunct,'_ismbbkpunct',\
       _ismbblead,'_ismbblead',\
       _ismbbprint,'_ismbbprint',\
       _ismbbpunct,'_ismbbpunct',\
       _ismbbtrail,'_ismbbtrail',\
       _ismbcalnum,'_ismbcalnum',\
       _ismbcalpha,'_ismbcalpha',\
       _ismbcdigit,'_ismbcdigit',\
       _ismbcgraph,'_ismbcgraph',\
       _ismbchira,'_ismbchira',\
       _ismbckata,'_ismbckata',\
       _ismbcl0,'_ismbcl0',\
       _ismbcl1,'_ismbcl1',\
       _ismbcl2,'_ismbcl2',\
       _ismbclegal,'_ismbclegal',\
       _ismbclower,'_ismbclower',\
       _ismbcprint,'_ismbcprint',\
       _ismbcpunct,'_ismbcpunct',\
       _ismbcspace,'_ismbcspace',\
       _ismbcsymbol,'_ismbcsymbol',\
       _ismbcupper,'_ismbcupper',\
       _ismbslead,'_ismbslead',\
       _ismbstrail,'_ismbstrail',\
       _isnan,'_isnan',\
       _itoa,'_itoa',\
       _itow,'_itow',\
       _j0,'_j0',\
       _j1,'_j1',\
       _jn,'_jn',\
       _kbhit,'_kbhit',\
       _lfind,'_lfind',\
       _loaddll,'_loaddll',\
       _local_unwind2,'_local_unwind2',\
       _localtime64,'_localtime64',\
       _lock,'_lock',\
       _locking,'_locking',\
       _logb,'_logb',\
       _longjmpex,'_longjmpex',\
       _lrotl,'_lrotl',\
       _lrotr,'_lrotr',\
       _lsearch,'_lsearch',\
       _lseek,'_lseek',\
       _lseeki64,'_lseeki64',\
       _ltoa,'_ltoa',\
       _ltow,'_ltow',\
       _makepath,'_makepath',\
       _mbbtombc,'_mbbtombc',\
       _mbbtype,'_mbbtype',\
       _mbcasemap,'_mbcasemap',\
       _mbccpy,'_mbccpy',\
       _mbcjistojms,'_mbcjistojms',\
       _mbcjmstojis,'_mbcjmstojis',\
       _mbclen,'_mbclen',\
       _mbctohira,'_mbctohira',\
       _mbctokata,'_mbctokata',\
       _mbctolower,'_mbctolower',\
       _mbctombb,'_mbctombb',\
       _mbctoupper,'_mbctoupper',\
       _mbctype,'_mbctype',\
       _mbsbtype,'_mbsbtype',\
       _mbscat,'_mbscat',\
       _mbschr,'_mbschr',\
       _mbscmp,'_mbscmp',\
       _mbscoll,'_mbscoll',\
       _mbscpy,'_mbscpy',\
       _mbscspn,'_mbscspn',\
       _mbsdec,'_mbsdec',\
       _mbsdup,'_mbsdup',\
       _mbsicmp,'_mbsicmp',\
       _mbsicoll,'_mbsicoll',\
       _mbsinc,'_mbsinc',\
       _mbslen,'_mbslen',\
       _mbslwr,'_mbslwr',\
       _mbsnbcat,'_mbsnbcat',\
       _mbsnbcmp,'_mbsnbcmp',\
       _mbsnbcnt,'_mbsnbcnt',\
       _mbsnbcoll,'_mbsnbcoll',\
       _mbsnbcpy,'_mbsnbcpy',\
       _mbsnbicmp,'_mbsnbicmp',\
       _mbsnbicoll,'_mbsnbicoll',\
       _mbsnbset,'_mbsnbset',\
       _mbsncat,'_mbsncat',\
       _mbsnccnt,'_mbsnccnt',\
       _mbsncmp,'_mbsncmp',\
       _mbsncoll,'_mbsncoll',\
       _mbsncpy,'_mbsncpy',\
       _mbsnextc,'_mbsnextc',\
       _mbsnicmp,'_mbsnicmp',\
       _mbsnicoll,'_mbsnicoll',\
       _mbsninc,'_mbsninc',\
       _mbsnset,'_mbsnset',\
       _mbspbrk,'_mbspbrk',\
       _mbsrchr,'_mbsrchr',\
       _mbsrev,'_mbsrev',\
       _mbsset,'_mbsset',\
       _mbsspn,'_mbsspn',\
       _mbsspnp,'_mbsspnp',\
       _mbsstr,'_mbsstr',\
       _mbstok,'_mbstok',\
       _mbstrlen,'_mbstrlen',\
       _mbsupr,'_mbsupr',\
       _memccpy,'_memccpy',\
       _memicmp,'_memicmp',\
       _mkdir,'_mkdir',\
       _mktemp,'_mktemp',\
       _mktime64,'_mktime64',\
       _msize,'_msize',\
       _nextafter,'_nextafter',\
       _onexit,'_onexit',\
       _open,'_open',\
       _open_osfhandle,'_open_osfhandle',\
       _osplatform,'_osplatform',\
       _osver,'_osver',\
       _outp,'_outp',\
       _outpd,'_outpd',\
       _outpw,'_outpw',\
       _pclose,'_pclose',\
       _pctype,'_pctype',\
       _pgmptr,'_pgmptr',\
       _pipe,'_pipe',\
       _popen,'_popen',\
       _purecall,'_purecall',\
       _putch,'_putch',\
       _putenv,'_putenv',\
       _putw,'_putw',\
       _putwch,'_putwch',\
       _putws,'_putws',\
       _pwctype,'_pwctype',\
       _read,'_read',\
       _resetstkoflw,'_resetstkoflw',\
       _rmdir,'_rmdir',\
       _rmtmp,'_rmtmp',\
       _rotl,'_rotl',\
       _rotr,'_rotr',\
       _safe_fdiv,'_safe_fdiv',\
       _safe_fdivr,'_safe_fdivr',\
       _safe_fprem,'_safe_fprem',\
       _safe_fprem1,'_safe_fprem1',\
       _scalb,'_scalb',\
       _scprintf,'_scprintf',\
       _scwprintf,'_scwprintf',\
       _searchenv,'_searchenv',\
       _seh_longjmp_unwind,'_seh_longjmp_unwind',\
       _set_SSE2_enable,'_set_SSE2_enable',\
       _set_error_mode,'_set_error_mode',\
       _set_sbh_threshold,'_set_sbh_threshold',\
       _seterrormode,'_seterrormode',\
       _setjmp,'_setjmp',\
       _setjmp3,'_setjmp3',\
       _setmaxstdio,'_setmaxstdio',\
       _setmbcp,'_setmbcp',\
       _setmode,'_setmode',\
       _setsystime,'_setsystime',\
       _sleep,'_sleep',\
       _snprintf,'_snprintf',\
       _snscanf,'_snscanf',\
       _snwprintf,'_snwprintf',\
       _snwscanf,'_snwscanf',\
       _sopen,'_sopen',\
       _spawnl,'_spawnl',\
       _spawnle,'_spawnle',\
       _spawnlp,'_spawnlp',\
       _spawnlpe,'_spawnlpe',\
       _spawnv,'_spawnv',\
       _spawnve,'_spawnve',\
       _spawnvp,'_spawnvp',\
       _spawnvpe,'_spawnvpe',\
       _splitpath,'_splitpath',\
       _stat,'_stat',\
       _stat64,'_stat64',\
       _stati64,'_stati64',\
       _statusfp,'_statusfp',\
       _strcmpi,'_strcmpi',\
       _strdate,'_strdate',\
       _strdup,'_strdup',\
       _strerror,'_strerror',\
       _stricmp,'_stricmp',\
       _stricoll,'_stricoll',\
       _strlwr,'_strlwr',\
       _strncoll,'_strncoll',\
       _strnicmp,'_strnicmp',\
       _strnicoll,'_strnicoll',\
       _strnset,'_strnset',\
       _strrev,'_strrev',\
       _strset,'_strset',\
       _strtime,'_strtime',\
       _strtoi64,'_strtoi64',\
       _strtoui64,'_strtoui64',\
       _strupr,'_strupr',\
       _swab,'_swab',\
       _sys_errlist,'_sys_errlist',\
       _sys_nerr,'_sys_nerr',\
       _tell,'_tell',\
       _telli64,'_telli64',\
       _tempnam,'_tempnam',\
       _time64,'_time64',\
       _timezone,'_timezone',\
       _tolower,'_tolower',\
       _toupper,'_toupper',\
       _tzname,'_tzname',\
       _tzset,'_tzset',\
       _ui64toa,'_ui64toa',\
       _ui64tow,'_ui64tow',\
       _ultoa,'_ultoa',\
       _ultow,'_ultow',\
       _umask,'_umask',\
       _ungetch,'_ungetch',\
       _ungetwch,'_ungetwch',\
       _unlink,'_unlink',\
       _unloaddll,'_unloaddll',\
       _unlock,'_unlock',\
       _utime,'_utime',\
       _utime64,'_utime64',\
       _vscprintf,'_vscprintf',\
       _vscwprintf,'_vscwprintf',\
       _vsnprintf,'_vsnprintf',\
       _vsnwprintf,'_vsnwprintf',\
       _waccess,'_waccess',\
       _wasctime,'_wasctime',\
       _wchdir,'_wchdir',\
       _wchmod,'_wchmod',\
       _wcmdln,'_wcmdln',\
       _wcreat,'_wcreat',\
       _wcsdup,'_wcsdup',\
       _wcserror,'_wcserror',\
       _wcsicmp,'_wcsicmp',\
       _wcsicoll,'_wcsicoll',\
       _wcslwr,'_wcslwr',\
       _wcsncoll,'_wcsncoll',\
       _wcsnicmp,'_wcsnicmp',\
       _wcsnicoll,'_wcsnicoll',\
       _wcsnset,'_wcsnset',\
       _wcsrev,'_wcsrev',\
       _wcsset,'_wcsset',\
       _wcstoi64,'_wcstoi64',\
       _wcstoui64,'_wcstoui64',\
       _wcsupr,'_wcsupr',\
       _wctime,'_wctime',\
       _wctime64,'_wctime64',\
       _wenviron,'_wenviron',\
       _wexecl,'_wexecl',\
       _wexecle,'_wexecle',\
       _wexeclp,'_wexeclp',\
       _wexeclpe,'_wexeclpe',\
       _wexecv,'_wexecv',\
       _wexecve,'_wexecve',\
       _wexecvp,'_wexecvp',\
       _wexecvpe,'_wexecvpe',\
       _wfdopen,'_wfdopen',\
       _wfindfirst,'_wfindfirst',\
       _wfindfirst64,'_wfindfirst64',\
       _wfindfirsti64,'_wfindfirsti64',\
       _wfindnext,'_wfindnext',\
       _wfindnext64,'_wfindnext64',\
       _wfindnexti64,'_wfindnexti64',\
       _wfopen,'_wfopen',\
       _wfreopen,'_wfreopen',\
       _wfsopen,'_wfsopen',\
       _wfullpath,'_wfullpath',\
       _wgetcwd,'_wgetcwd',\
       _wgetdcwd,'_wgetdcwd',\
       _wgetenv,'_wgetenv',\
       _winmajor,'_winmajor',\
       _winminor,'_winminor',\
       _winver,'_winver',\
       _wmakepath,'_wmakepath',\
       _wmkdir,'_wmkdir',\
       _wmktemp,'_wmktemp',\
       _wopen,'_wopen',\
       _wperror,'_wperror',\
       _wpgmptr,'_wpgmptr',\
       _wpopen,'_wpopen',\
       _wputenv,'_wputenv',\
       _wremove,'_wremove',\
       _wrename,'_wrename',\
       _write,'_write',\
       _wrmdir,'_wrmdir',\
       _wsearchenv,'_wsearchenv',\
       _wsetlocale,'_wsetlocale',\
       _wsopen,'_wsopen',\
       _wspawnl,'_wspawnl',\
       _wspawnle,'_wspawnle',\
       _wspawnlp,'_wspawnlp',\
       _wspawnlpe,'_wspawnlpe',\
       _wspawnv,'_wspawnv',\
       _wspawnve,'_wspawnve',\
       _wspawnvp,'_wspawnvp',\
       _wspawnvpe,'_wspawnvpe',\
       _wsplitpath,'_wsplitpath',\
       _wstat,'_wstat',\
       _wstat64,'_wstat64',\
       _wstati64,'_wstati64',\
       _wstrdate,'_wstrdate',\
       _wstrtime,'_wstrtime',\
       _wsystem,'_wsystem',\
       _wtempnam,'_wtempnam',\
       _wtmpnam,'_wtmpnam',\
       _wtof,'_wtof',\
       _wtoi,'_wtoi',\
       _wtoi64,'_wtoi64',\
       _wtol,'_wtol',\
       _wunlink,'_wunlink',\
       _wutime,'_wutime',\
       _wutime64,'_wutime64',\
       _y0,'_y0',\
       _y1,'_y1',\
       _yn,'_yn',\
       abort,'abort',\
       abs,'abs',\
       acos,'acos',\
       asctime,'asctime',\
       asin,'asin',\
       atan,'atan',\
       atan2,'atan2',\
       atexit,'atexit',\
       atof,'atof',\
       atoi,'atoi',\
       atol,'atol',\
       bsearch,'bsearch',\
       calloc,'calloc',\
       ceil,'ceil',\
       clearerr,'clearerr',\
       clock,'clock',\
       cos,'cos',\
       cosh,'cosh',\
       ctime,'ctime',\
       difftime,'difftime',\
       cdiv,'div',\
       exit,'exit',\
       exp,'exp',\
       cfabs,'fabs',\
       fclose,'fclose',\
       feof,'feof',\
       ferror,'ferror',\
       fflush,'fflush',\
       fgetc,'fgetc',\
       fgetpos,'fgetpos',\
       fgets,'fgets',\
       fgetwc,'fgetwc',\
       fgetws,'fgetws',\
       floor,'floor',\
       fmod,'fmod',\
       fopen,'fopen',\
       fprintf,'fprintf',\
       fputc,'fputc',\
       fputs,'fputs',\
       fputwc,'fputwc',\
       fputws,'fputws',\
       fread,'fread',\
       free,'free',\
       freopen,'freopen',\
       frexp,'frexp',\
       fscanf,'fscanf',\
       fseek,'fseek',\
       fsetpos,'fsetpos',\
       ftell,'ftell',\
       fwprintf,'fwprintf',\
       fwrite,'fwrite',\
       fwscanf,'fwscanf',\
       getc,'getc',\
       getchar,'getchar',\
       getenv,'getenv',\
       gets,'gets',\
       getwc,'getwc',\
       getwchar,'getwchar',\
       gmtime,'gmtime',\
       is_wctype,'is_wctype',\
       isalnum,'isalnum',\
       isalpha,'isalpha',\
       iscntrl,'iscntrl',\
       isdigit,'isdigit',\
       isgraph,'isgraph',\
       isleadbyte,'isleadbyte',\
       islower,'islower',\
       isprint,'isprint',\
       ispunct,'ispunct',\
       isspace,'isspace',\
       isupper,'isupper',\
       iswalnum,'iswalnum',\
       iswalpha,'iswalpha',\
       iswascii,'iswascii',\
       iswcntrl,'iswcntrl',\
       iswctype,'iswctype',\
       iswdigit,'iswdigit',\
       iswgraph,'iswgraph',\
       iswlower,'iswlower',\
       iswprint,'iswprint',\
       iswpunct,'iswpunct',\
       iswspace,'iswspace',\
       iswupper,'iswupper',\
       iswxdigit,'iswxdigit',\
       isxdigit,'isxdigit',\
       labs,'labs',\
       ldexp,'ldexp',\
       ldiv,'ldiv',\
       localeconv,'localeconv',\
       localtime,'localtime',\
       log,'log',\
       log10,'log10',\
       longjmp,'longjmp',\
       malloc,'malloc',\
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       mbstowcs,'mbstowcs',\
       mbtowc,'mbtowc',\
       memchr,'memchr',\
       memcmp,'memcmp',\
       memcpy,'memcpy',\
       memmove,'memmove',\
       memset,'memset',\
       mktime,'mktime',\
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       perror,'perror',\
       pow,'pow',\
       printf,'printf',\
       putc,'putc',\
       putchar,'putchar',\
       puts,'puts',\
       putwc,'putwc',\
       putwchar,'putwchar',\
       qsort,'qsort',\
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       rand,'rand',\
       realloc,'realloc',\
       remove,'remove',\
       rename,'rename',\
       rewind,'rewind',\
       scanf,'scanf',\
       setbuf,'setbuf',\
       setlocale,'setlocale',\
       setvbuf,'setvbuf',\
       signal,'signal',\
       sin,'sin',\
       sinh,'sinh',\
       sprintf,'sprintf',\
       sqrt,'sqrt',\
       srand,'srand',\
       sscanf,'sscanf',\
       strcat,'strcat',\
       strchr,'strchr',\
       strcmp,'strcmp',\
       strcoll,'strcoll',\
       strcpy,'strcpy',\
       strcspn,'strcspn',\
       strerror,'strerror',\
       strftime,'strftime',\
       strlen,'strlen',\
       strncat,'strncat',\
       strncmp,'strncmp',\
       strncpy,'strncpy',\
       strpbrk,'strpbrk',\
       strrchr,'strrchr',\
       strspn,'strspn',\
       strstr,'strstr',\
       strtod,'strtod',\
       strtok,'strtok',\
       strtol,'strtol',\
       strtoul,'strtoul',\
       strxfrm,'strxfrm',\
       swprintf,'swprintf',\
       swscanf,'swscanf',\
       system,'system',\
       tan,'tan',\
       tanh,'tanh',\
       time,'time',\
       tmpfile,'tmpfile',\
       tmpnam,'tmpnam',\
       tolower,'tolower',\
       toupper,'toupper',\
       towlower,'towlower',\
       towupper,'towupper',\
       ungetc,'ungetc',\
       ungetwc,'ungetwc',\
       vfprintf,'vfprintf',\
       vfwprintf,'vfwprintf',\
       vprintf,'vprintf',\
       vsprintf,'vsprintf',\
       vswprintf,'vswprintf',\
       vwprintf,'vwprintf',\
       wcscat,'wcscat',\
       wcschr,'wcschr',\
       wcscmp,'wcscmp',\
       wcscoll,'wcscoll',\
       wcscpy,'wcscpy',\
       wcscspn,'wcscspn',\
       wcsftime,'wcsftime',\
       wcslen,'wcslen',\
       wcsncat,'wcsncat',\
       wcsncmp,'wcsncmp',\
       wcsncpy,'wcsncpy',\
       wcspbrk,'wcspbrk',\
       wcsrchr,'wcsrchr',\
       wcsspn,'wcsspn',\
       wcsstr,'wcsstr',\
       wcstod,'wcstod',\
       wcstok,'wcstok',\
       wcstol,'wcstol',\
       wcstombs,'wcstombs',\
       wcstoul,'wcstoul',\
       wcsxfrm,'wcsxfrm',\
       wctomb,'wctomb',\
       wprintf,'wprintf',\
       wscanf,'wscanf'

25 Jul 2009, 19:07

Borsuc

Joined: 29 Dec 2005
Posts: 2465
Location: Bucharest, Romania

Borsuc 25 Jul 2009, 19:48

asmcoder wrote:

2.5 - you can sacrifice 8 bits to write after .

2.5 = 00000010 00000101

LOL

That's not a 'five', it's 2 and half, so it should be:

00000010 10000000

Laughing

_________________
Previously known as The_Grey_Beast

25 Jul 2009, 19:48

Madis731

Joined: 25 Sep 2003
Posts: 2139
Location: Estonia

Madis731 25 Jul 2009, 21:32

I tried finding out how C compilers manage with pow(double,double), but it never inlines it Sad

only calls. Where's the source?

25 Jul 2009, 21:32

r22

Joined: 27 Dec 2004
Posts: 805

r22 25 Jul 2009, 21:47

I recall decompiling Intel's or AMD's math library when I was interested in their SIMD trig function approximations, they used some very exotic tricks but I settled on a Taylor series for sine and cosine.

Fanael wrote:

pow(x, y) = exp(ln(x) * y)

This is your best method.

LN(base) using the x87's FYL2X ST(0) = base ST(1) = FLDLN2
EXP(x) using the series EXP(x) = SUM[n=0->INF]( x^n / n! ),
EDIT Too many iterations to get accuracy

Last edited by r22 on 25 Jul 2009, 23:51; edited 1 time in total

25 Jul 2009, 21:47

LocoDelAssembly
Your code has a bug

Joined: 06 May 2005
Posts: 4624
Location: Argentina

LocoDelAssembly 25 Jul 2009, 21:54

Madis, but note that inlining that function every time may be a little bit overkill. The SSE version of it is HUGE, really, it is surprising it is yet faster (haven't checked it really is, I'm just assuming they are not misusing SSE).

To give an idea of how huge it is, when __pow_pentium4 started to be executed I did 180 single steps to return from it (caller was "pow(3, 2.5)").

25 Jul 2009, 21:54

Fanael

Joined: 03 Jul 2009
Posts: 168

Fanael 25 Jul 2009, 23:20

Maybe this one works:

Code:

fld qword [y] ;size of double is equal to size of qword, isn't it?
fld qword [x]
fyl2x
fld st0
frndint
fsub st1, st0
fxch st1
f2xm1
fld1
faddp st1, st0
fscale
fstp st1

After that, st0 should contain x^y... Maybe...

25 Jul 2009, 23:20

bitshifter

Joined: 04 Dec 2007
Posts: 796
Location: Massachusetts, USA

bitshifter 26 Jul 2009, 04:11

My other option is to sit on 68 bytes of gamma table.
I thought it would be nice by creating it on the fly
this would allow the user to choose gamma factor.

26 Jul 2009, 04:11

Madis731

Joined: 25 Sep 2003
Posts: 2139
Location: Estonia

Madis731 26 Jul 2009, 08:04

I also traced it through and couldn't understand what it was doing.
http://jrfonseca.blogspot.com/2008/09/fast-sse2-pow-tables-or-polynomials.html some link I found...

Fanael's code looks okay, but only fails in cases where X is negative for example -0.5^-4 or -0.5^4, but is is easily fixable Smile

EDIT: no, its not simple :S -0.5^1 is negative, -0.5^2 is positive and -0.5^2.1 is invalid

Smile

Just make sure that the input is positive and you're set

26 Jul 2009, 08:04

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