83 lines
1.8 KiB
C
83 lines
1.8 KiB
C
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/* Bra86.c -- Converter for x86 code (BCJ)
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2017-04-03 : Igor Pavlov : Public domain */
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#include "Precomp.h"
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#include "Bra.h"
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#define Test86MSByte(b) ((((b) + 1) & 0xFE) == 0)
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SizeT x86_Convert(Byte *data, SizeT size, UInt32 ip, UInt32 *state, int encoding)
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{
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SizeT pos = 0;
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UInt32 mask = *state & 7;
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if (size < 5)
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return 0;
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size -= 4;
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ip += 5;
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for (;;)
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{
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Byte *p = data + pos;
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const Byte *limit = data + size;
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for (; p < limit; p++)
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if ((*p & 0xFE) == 0xE8)
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break;
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{
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SizeT d = (SizeT)(p - data - pos);
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pos = (SizeT)(p - data);
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if (p >= limit)
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{
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*state = (d > 2 ? 0 : mask >> (unsigned)d);
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return pos;
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}
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if (d > 2)
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mask = 0;
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else
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{
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mask >>= (unsigned)d;
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if (mask != 0 && (mask > 4 || mask == 3 || Test86MSByte(p[(size_t)(mask >> 1) + 1])))
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{
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mask = (mask >> 1) | 4;
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pos++;
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continue;
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}
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}
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}
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if (Test86MSByte(p[4]))
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{
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UInt32 v = ((UInt32)p[4] << 24) | ((UInt32)p[3] << 16) | ((UInt32)p[2] << 8) | ((UInt32)p[1]);
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UInt32 cur = ip + (UInt32)pos;
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pos += 5;
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if (encoding)
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v += cur;
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else
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v -= cur;
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if (mask != 0)
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{
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unsigned sh = (mask & 6) << 2;
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if (Test86MSByte((Byte)(v >> sh)))
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{
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v ^= (((UInt32)0x100 << sh) - 1);
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if (encoding)
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v += cur;
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else
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v -= cur;
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}
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mask = 0;
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}
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p[1] = (Byte)v;
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p[2] = (Byte)(v >> 8);
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p[3] = (Byte)(v >> 16);
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p[4] = (Byte)(0 - ((v >> 24) & 1));
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}
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else
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{
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mask = (mask >> 1) | 4;
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pos++;
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}
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}
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}
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