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Prefix decoding improved

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This commit is contained in:
Nekotekina 2015-01-04 18:33:25 +03:00
parent 896097da0d
commit 22497757e9
1 changed files with 55 additions and 18 deletions
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73
rpcs3/Emu/CPU/CPUThread.cpp
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@ -290,26 +290,63 @@ void decode_x64_reg_op(const u8* code, x64_op_t& decoded_op, x64_reg_t& decoded_
{
decoded_size = 0;
u8 reg = 0;
if ((*code & 0xf0) == 0x40) // check REX prefix
{
if (*code & 0x80) // check REX.W bit
{
throw fmt::Format("decode_x64_reg_op(%.16llXh): REX.W bit found", code - decoded_size);
}
if (*code & 0x04) // check REX.R bit
{
reg = 8;
}
code++;
decoded_size++;
}
u8 rex = 0;
u8 reg = 0; // set to 8 by REX prefix
u8 pg2 = 0;
if (*code == 0x66)
// check prefixes:
for (;; code++, decoded_size++)
{
throw fmt::Format("decode_x64_reg_op(%.16llXh): 0x66 prefix found", code - decoded_size);
code++;
decoded_size++;
switch (const u8 prefix = *code)
{
case 0xf0: throw fmt::Format("decode_x64_reg_op(%.16llXh): 0x%.2X (LOCK prefix) found", code - decoded_size, prefix); // group 1
case 0xf2: throw fmt::Format("decode_x64_reg_op(%.16llXh): 0x%.2X (REPNE/REPNZ prefix) found", code - decoded_size, prefix); // group 1
case 0xf3: throw fmt::Format("decode_x64_reg_op(%.16llXh): 0x%.2X (REP/REPE/REPZ prefix) found", code - decoded_size, prefix); // group 1
case 0x2e: // group 2
case 0x36:
case 0x3e:
case 0x26:
case 0x64:
case 0x65:
{
if (!pg2)
{
pg2 = prefix; // probably, segment selector
continue;
}
else
{
throw fmt::Format("decode_x64_reg_op(%.16llXh): 0x%.2X (group 2 prefix) found after 0x%.2X", code - decoded_size, prefix, pg2);
}
}
case 0x66: throw fmt::Format("decode_x64_reg_op(%.16llXh): 0x%.2X (operand-size override prefix) found", code - decoded_size, prefix); // group 3
case 0x67: throw fmt::Format("decode_x64_reg_op(%.16llXh): 0x%.2X (address-size override prefix) found", code - decoded_size, prefix); // group 4
default:
{
if ((prefix & 0xf0) == 0x40) // check REX prefix
{
if (rex)
{
throw fmt::Format("decode_x64_reg_op(%.16llXh): 0x%.2X (REX prefix) found after 0x%.2X", code - decoded_size, prefix, rex);
}
if (prefix & 0x80) // check REX.W bit
{
throw fmt::Format("decode_x64_reg_op(%.16llXh): 0x%.2X (REX.W bit) found", code - decoded_size, prefix);
}
if (prefix & 0x04) // check REX.R bit
{
reg = 8;
}
rex = prefix;
continue;
}
}
}
break;
}
auto get_modRM_r32 = [](const u8* code, const u8 reg_base) -> x64_reg_t