forked from KolibriOS/kolibrios
127 lines
3.3 KiB
PHP
127 lines
3.3 KiB
PHP
; ----------------------------- MOTHER.ASM -----------------------------
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; Mother-of-All random number generator by Agner Fog 1998
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; 32-bit mode version for 80x86 and compatible microprocessors
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;
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; MRandom returns a floating point number between 0 and 1.
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; MRandomInit must be called before the first call to MRandom.
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;
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; C++ prototypes:
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; extern "C" void MRandomInit (int seed);
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; extern "C" double MRandom (void);
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; extern "C" int MIRandom (int min, int max);
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;
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; © 1998, 2004 Agner Fog.
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; GNU General Public License www.gnu.org/copyleft/gpl.html
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; ----------------------------------------------------------------------
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; The MRandom function is optimized for the Pentium microprocessor.
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iglobal
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mf3 dd 2111111111 ; factors
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mf2 dd 1492
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mf1 dd 1776
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mf0 dd 5115
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endg
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uglobal
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m0 dd ? ; history buffer
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m1 dd ?
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m2 dd ?
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m3 dd ?
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mc dd ?
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temprng dq ? ; used for conversion to float
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endg
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proc init_random
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mcall 26, 10 ; seed
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xor ecx, ecx
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; make random numbers and put them into buffer
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@@:
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imul eax, 29943829
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dec eax
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mov [m0+ecx*4], eax
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inc ecx
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cmp ecx, 5
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jb @r
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push edi
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mov edi, 19
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@@:
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call MRandom
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fstp st0
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dec edi
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jnz @r
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pop edi
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ret
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endp
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proc MRandom
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call MBRandom ; random bits
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mov edx, eax ; fast conversion to float
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shr eax, 12
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or eax, 3ff00000h
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shl edx, 20
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mov dword[temprng+4], eax
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mov dword[temprng], edx
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fld1
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fld [temprng] ; partial memory stall here
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fsubr st0, st1
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ret
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endp
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proc MIRandom, max, min ; make random integer in desired interval
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call MBRandom ; make random number
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mov edx, [max]
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mov ecx, [min]
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sub edx, ecx
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js .error ; max < min
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inc edx ; max - min + 1
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mul edx ; multiply random number by interval and truncate
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lea eax, [edx+ecx] ; add min
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ret
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.error:
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mov eax, 80000000h ; error exit
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ret
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endp
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proc MBRandom
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push edi
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mov eax, [mf3]
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mul [m3] ; x[n-4]
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mov ecx, eax
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mov eax, [m2] ; x[n-3]
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mov edi, edx
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mov [m3], eax
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mul [mf2]
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add ecx, eax
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mov eax, [m1] ; x[n-2]
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adc edi, edx
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mov [m2], eax
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mul [mf1]
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add ecx, eax
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mov eax, [m0] ; x[n-1]
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adc edi, edx
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mov [m1], eax
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mul [mf0]
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add eax, ecx
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adc edx, edi
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add eax, [mc]
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adc edx, 0
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mov [m0], eax
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mov [mc], edx
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pop edi
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ret
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endp |