forked from KolibriOS/kolibrios
568 lines
13 KiB
PHP
568 lines
13 KiB
PHP
; mpint.inc - Multi precision integer procedures
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;
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; Copyright (C) 2015-2016 Jeffrey Amelynck
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;
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; This program is free software: you can redistribute it and/or modify
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; it under the terms of the GNU General Public License as published by
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; the Free Software Foundation, either version 3 of the License, or
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; (at your option) any later version.
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;
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; This program is distributed in the hope that it will be useful,
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; but WITHOUT ANY WARRANTY; without even the implied warranty of
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; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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; GNU General Public License for more details.
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;
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; You should have received a copy of the GNU General Public License
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; along with this program. If not, see <http://www.gnu.org/licenses/>.
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MPINT_MAX_LEN = MAX_BITS/8
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; TODO: make procedures use real number length instead of hardcoded maximum length (MPINT_MAX_LEN)
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mpint_to_little_endian:
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; Load length dword
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lodsd
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; Convert to little endian
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bswap eax
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stosd
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test eax, eax
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jz .zero
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; Copy data, convert to little endian meanwhile
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push eax
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add esi, eax
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push esi
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dec esi
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mov ecx, eax
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std
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@@:
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lodsb
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mov byte[edi], al
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inc edi
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dec ecx
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jnz @r
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cld
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pop esi eax
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; Fill the rest of the buffer with zeros.
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.zero:
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mov ecx, MAX_BITS/8
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sub ecx, eax
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xor al, al
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rep stosb
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ret
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mpint_to_big_endian:
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; Load length dword
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lodsd
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test eax, eax
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jz .zero
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mov ecx, eax
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add esi, ecx
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dec esi
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test byte[esi], 0x80 ; Is the highest bit set?
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jz @f
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inc eax
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@@:
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push eax
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bswap eax
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stosd
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; Copy data, convert to big endian meanwhile
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std
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; Append zero byte if highest bit is 0
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test byte[esi], 0x80
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jz @f
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mov byte[edi], 0
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inc edi
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@@:
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lodsb
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mov byte[edi], al
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inc edi
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dec ecx
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jnz @r
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cld
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pop eax
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ret
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.zero:
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stosd
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ret
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proc mpint_length uses edi eax ecx, mpint
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mov edi, [mpint]
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mov ecx, MPINT_MAX_LEN
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push edi
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lea edi, [edi + ecx + 4 - 1]
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xor al, al
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std
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repe scasb
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cld
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je @f
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inc ecx
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@@:
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pop edi
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mov [edi], ecx
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ret
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endp
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proc mpint_print uses ecx esi eax, src
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DEBUGF 1, "0x"
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mov esi, [src]
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mov ecx, [esi]
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test ecx, ecx
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jz .zero
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lea esi, [esi + ecx + 4 - 1]
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pushf
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std
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.loop:
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lodsb
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DEBUGF 1, "%x", eax:2
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dec ecx
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jnz .loop
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DEBUGF 1, "\n"
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popf
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ret
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.zero:
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DEBUGF 1, "00\n"
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ret
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endp
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proc mpint_zero uses edi ecx eax, dst
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mov edi, [dst]
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xor eax, eax
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mov ecx, MPINT_MAX_LEN/4+1
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rep stosd
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ret
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endp
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proc mpint_zero? uses edi ecx eax, dst
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mov edi, [dst]
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add edi, 4
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mov ecx, MPINT_MAX_LEN/4
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xor eax, eax
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repe scasd
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ret
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endp
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; return an index number giving the position of the highest order bit
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proc mpint_hob uses edi ecx, dst
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mov edi, [dst]
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; start from the high order byte
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add edi, MPINT_MAX_LEN+4-1
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mov ecx, MPINT_MAX_LEN
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xor eax, eax
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; scan byte by byte for the first non-zero byte
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std
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repe scasb
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cld
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je .zero
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; calculate how many bits this is, plus 7
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lea eax, [ecx*8-1]
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; load this high order byte into cl
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mov cl, [edi+1]
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; shift bits of this byte right, until the byte reaches zero, counting bits meanwhile
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@@:
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inc eax
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shr cl, 1
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jnz @r
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.zero:
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ret
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endp
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proc mpint_cmp uses esi edi ecx, dst, src
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mov esi, [src]
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mov edi, [dst]
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; start from the high order byte
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add esi, MPINT_MAX_LEN+4-4
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add edi, MPINT_MAX_LEN+4-4
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mov ecx, MPINT_MAX_LEN/4
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std
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repe cmpsd
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cld
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ret
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endp
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proc mpint_mov uses esi edi ecx, dst, src
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mov esi, [src]
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mov edi, [dst]
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mov ecx, MPINT_MAX_LEN/4+1
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rep movsd
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ret
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endp
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proc mpint_mov0 uses esi edi ecx eax, dst, src
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mov esi, [src]
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mov edi, [dst]
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mov ecx, [esi]
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mov eax, ecx
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neg eax
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add esi, 4
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add edi, 4
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rep movsb
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add eax, MPINT_MAX_LEN
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jz @f
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mov ecx, eax
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xor eax, eax
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rep stosb
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@@:
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ret
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endp
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proc mpint_shl1 uses edi ecx eax, dst
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mov edi, [dst]
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add edi, 4
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mov ecx, MPINT_MAX_LEN/4-1
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shl dword[edi], 1
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lahf
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@@:
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add edi, 4
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sahf
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rcl dword[edi], 1
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lahf
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dec ecx
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jnz @r
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sahf
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ret
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endp
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proc mpint_shr1 uses edi ecx eax, dst
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mov edi, [dst]
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add edi, MPINT_MAX_LEN+4-4
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mov ecx, MPINT_MAX_LEN/4-1
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shr dword[edi], 1
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lahf
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@@:
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sub edi, 4
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sahf
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rcr dword[edi], 1
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lahf
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dec ecx
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jnz @r
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sahf
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ret
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endp
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proc mpint_shl uses eax ebx ecx edx esi edi, dst, shift
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mov ecx, [shift]
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shr ecx, 3 ; 8 bits in one byte
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cmp ecx, MPINT_MAX_LEN
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jge .zero
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mov esi, [dst]
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add esi, MPINT_MAX_LEN+4-4
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mov edi, esi
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and ecx, not 11b
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sub esi, ecx
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mov edx, MPINT_MAX_LEN/4-1
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shr ecx, 2 ; 4 bytes in one dword
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push ecx
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sub edx, ecx
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mov ecx, [shift]
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and ecx, 11111b
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std
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.loop:
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lodsd
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mov ebx, [esi]
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shld eax, ebx, cl
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stosd
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dec edx
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jnz .loop
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lodsd
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shl eax, cl
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stosd
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; fill the lsb bytes with zeros
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pop ecx
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test ecx, ecx
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jz @f
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xor eax, eax
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rep stosd
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@@:
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cld
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ret
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.zero:
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stdcall mpint_zero, [dst]
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ret
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endp
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; Left shift and copy
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proc mpint_shlmov uses eax ebx ecx edx esi edi, dst, src, shift
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mov ecx, [shift]
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shr ecx, 3 ; 8 bits in one byte
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cmp ecx, MPINT_MAX_LEN
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jge .zero
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mov esi, [src]
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add esi, MPINT_MAX_LEN+4-4
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mov edi, [dst]
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add edi, MPINT_MAX_LEN+4-4
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and ecx, not 11b
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sub esi, ecx
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mov edx, MPINT_MAX_LEN/4-1
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shr ecx, 2 ; 4 bytes in one dword
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push ecx
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sub edx, ecx
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mov ecx, [shift]
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and ecx, 11111b
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std
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.loop:
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lodsd
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mov ebx, [esi]
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shld eax, ebx, cl
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stosd
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dec edx
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jnz .loop
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lodsd
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shl eax, cl
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stosd
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; fill the lsb bytes with zeros
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pop ecx
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test ecx, ecx
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jz @f
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xor eax, eax
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rep stosd
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@@:
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cld
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ret
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.zero:
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stdcall mpint_zero, [dst]
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ret
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endp
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proc mpint_add uses esi edi ecx eax, dst, src
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mov esi, [src]
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add esi, 4
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mov edi, [dst]
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add edi, 4
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mov ecx, MPINT_MAX_LEN/4
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xor ah, ah ; clear flags (Carry flag most importantly)
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@@:
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sahf
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lodsd
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adc [edi], eax
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lahf
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add edi, 4
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dec ecx
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jnz @r
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sahf
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ret
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endp
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proc mpint_sub uses eax esi edi ecx, dst, src
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mov esi, [src]
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add esi, 4
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mov edi, [dst]
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add edi, 4
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mov ecx, MPINT_MAX_LEN/4
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; dst = dst + (NOT src) + 1
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stc ; Setting CF takes care of the +1
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pushf
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@@:
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lodsd
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not eax
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popf
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adc [edi], eax
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pushf
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add edi, 4
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dec ecx
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jnz @r
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popf
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ret
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endp
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proc mpint_mul uses esi edi ecx ebx eax, dst, A, B
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stdcall mpint_zero, [dst]
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; first, find the byte in A containing the highest order bit
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mov ecx, MPINT_MAX_LEN
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mov edi, [A]
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add edi, MPINT_MAX_LEN+4-1
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std
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xor al, al
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repe scasb
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cld
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je .zero
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inc ecx
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mov al, [edi+1]
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mov esi, edi
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mov bl, 8
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@@:
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shl al, 1
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jc .first_hit
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dec bl
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jnz @r
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; Then, starting from this byte, iterate through the bits in A,
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; starting from the highest order bit down to the lowest order bit.
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.next_byte:
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mov al, [edi]
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dec edi
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mov bl, 8
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.next_bit:
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stdcall mpint_shl1, [dst]
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shl al, 1
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jnc .zero_bit
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.first_hit:
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stdcall mpint_add, [dst], [B]
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.zero_bit:
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dec bl
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jnz .next_bit
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dec ecx
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jnz .next_byte
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.zero:
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ret
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endp
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proc mpint_mod uses eax ecx, dst, mod
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; if mod is zero, return
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stdcall mpint_zero?, [mod]
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jz .zero
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stdcall mpint_cmp, [mod], [dst]
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jb .done ; if dst < mod, dst = dst
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je .zero ; if dst == mod, dst = 0
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; left shift mod until the high order bits of mod and dst are aligned
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stdcall mpint_hob, [dst]
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mov ecx, eax
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stdcall mpint_hob, [mod]
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sub ecx, eax
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stdcall mpint_shlmov, mpint_tmp, [mod], ecx
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inc ecx
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; For every bit in dst (starting from the high order bit):
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.loop:
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; determine if dst is bigger than mpint_tmp
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stdcall mpint_cmp, [dst], mpint_tmp
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ja @f
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; if so, subtract mpint_tmp from dst
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stdcall mpint_sub, [dst], mpint_tmp
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@@:
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dec ecx
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jz .done
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; shift mpint_tmp right by 1
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stdcall mpint_shr1, mpint_tmp
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jmp .loop
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.zero:
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stdcall mpint_zero, [dst]
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.done:
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ret
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endp
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proc mpint_modexp uses edi eax ebx ecx, dst, base, exp, mod
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; If mod is zero, return
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stdcall mpint_zero?, [mod]
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jz .mod_zero
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; Find the highest order byte in exponent
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mov edi, [exp]
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mov ecx, [edi]
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lea edi, [edi + 4 + ecx - 1]
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; Find the highest order bit in this byte
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mov al, [edi]
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test al, al
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jz .invalid
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mov bl, 9
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@@:
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dec bl
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shl al, 1
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jnc @r
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; Initialise result to base, to take care of the highest order bit
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stdcall mpint_mov0, [dst], [base]
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dec bl
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jz .next_byte
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.bit_loop:
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; For each bit, square result
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stdcall mpint_mov, mpint_tmp, [dst]
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stdcall mpint_mul, [dst], mpint_tmp, mpint_tmp
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stdcall mpint_mod, [dst], [mod]
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; If the bit is set, multiply result by the base
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shl al, 1
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jnc .next_bit
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stdcall mpint_mov, mpint_tmp, [dst]
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stdcall mpint_mul, [dst], [base], mpint_tmp
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stdcall mpint_mod, [dst], [mod]
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.next_bit:
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dec bl
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jnz .bit_loop
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.next_byte:
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dec ecx
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jz .done
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dec edi
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mov al, [edi]
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mov bl, 8
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jmp .bit_loop
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.done:
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ret
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.mod_zero:
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DEBUGF 1, "modexp with modulo 0\n"
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; if mod is zero, result = 0
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stdcall mpint_zero, [dst]
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ret
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.exp_zero:
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DEBUGF 1, "modexp with exponent 0\n"
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; if exponent is zero, result = 1
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stdcall mpint_zero, [dst]
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mov eax, [dst]
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mov byte[eax], 1
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mov byte[eax+4], 1
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ret
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.invalid:
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DEBUGF 1, "modexp: Invalid input!\n"
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ret
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endp |