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Rev 6827 Rev 8130
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;;                                                              ;;
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;;                                                              ;;
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;; Copyright (C) KolibriOS team 2004-2017. All rights reserved. ;;
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;; Copyright (C) KolibriOS team 2004-2017. All rights reserved. ;;
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;;  Distributed under terms of the GNU General Public License.  ;;
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;;  Distributed under terms of the GNU General Public License.  ;;
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;;                                                              ;;
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;;                                                              ;;
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$Revision: 8130 $
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; This crc32 routine doesn't use precomputed table to allow different
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; This crc32 routine doesn't use precomputed table to allow different
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; polynomials, which is the first param.
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; polynomials, which is the first param.
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; Partial hash in assumed to be eax (both in and out).
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; Partial hash in assumed to be eax (both in and out).
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; Usage:
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; Usage:
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; 1. mov eax, -1
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; 1. mov eax, -1
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; 2. stdcall crypto.crc32 zero or more times
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; 2. stdcall crypto.crc32 zero or more times
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; 3. xor eax, -1
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; 3. xor eax, -1
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proc crc_32 _poly, _buffer, _length
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proc crc_32 _poly, _buffer, _length
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        push    ebx ecx edx esi
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        push    ebx ecx edx esi
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        mov     esi, [_buffer]
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        mov     esi, [_buffer]
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.next_byte:
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.next_byte:
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        dec     [_length]
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        dec     [_length]
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        js      .done
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        js      .done
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        movzx   ebx, byte[esi]
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        movzx   ebx, byte[esi]
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        inc     esi
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        inc     esi
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        mov     ecx, 8
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        mov     ecx, 8
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.next_bit:
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.next_bit:
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        mov     edx, eax
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        mov     edx, eax
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        xor     edx, ebx
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        xor     edx, ebx
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        shr     eax, 1
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        shr     eax, 1
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        test    edx, 1
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        test    edx, 1
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        jz      @f
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        jz      @f
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        xor     eax, [_poly]
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        xor     eax, [_poly]
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@@:
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@@:
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        shr     ebx, 1
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        shr     ebx, 1
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        dec     ecx
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        dec     ecx
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        jnz     .next_bit
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        jnz     .next_bit
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        jmp     .next_byte
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        jmp     .next_byte
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.done:
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.done:
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        pop     esi edx ecx ebx
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        pop     esi edx ecx ebx
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        ret
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        ret
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endp
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endp