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another small unsafe optimization

This commit is contained in:
thrust26 2019-02-25 19:50:33 +01:00
parent d716f42b5c
commit a251ccf3d6
1 changed files with 22 additions and 8 deletions
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26
src/emucore/Thumbulator.cxx
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@ -1688,7 +1688,11 @@ int Thumbulator::execute()
rb = (inst >> 6) & 0x1F;
DO_DISS(statusMsg << "ldrb r" << dec << rd << ",[r" << dec << rn << ",#0x" << Base::HEX2 << rb << "]" << endl);
rb = read_register(rn) + rb;
#ifndef UNSAFE_OPTIMIZATIONS
rc = read16(rb & (~1u));
#else
rc = read16(rb);
#endif
if(rb & 1)
{
rc >>= 8;
@ -1707,14 +1711,15 @@ int Thumbulator::execute()
rm = (inst >> 6) & 0x7;
DO_DISS(statusMsg << "ldrb r" << dec << rd << ",[r" << dec << rn << ",r" << dec << rm << "]" << endl);
rb = read_register(rn) + read_register(rm);
#ifndef UNSAFE_OPTIMIZATIONS
rc = read16(rb & (~1u));
#else
rc = read16(rb);
#endif
if(rb & 1)
{
rc >>= 8;
}
else
{
}
write_register(rd, rc & 0xFF);
return 0;
}
@ -1751,14 +1756,15 @@ int Thumbulator::execute()
rm = (inst >> 6) & 0x7;
DO_DISS(statusMsg << "ldrsb r" << dec << rd << ",[r" << dec << rn << ",r" << dec << rm << "]" << endl);
rb = read_register(rn) + read_register(rm);
#ifndef UNSAFE_OPTIMIZATIONS
rc = read16(rb & (~1u));
#else
rc = read16(rb);
#endif
if(rb & 1)
{
rc >>= 8;
}
else
{
}
rc &= 0xFF;
if(rc & 0x80)
rc |= ((~0u) << 8);
@ -2275,7 +2281,11 @@ int Thumbulator::execute()
DO_DISS(statusMsg << "strb r" << dec << rd << ",[r" << dec << rn << ",#0x" << Base::HEX8 << rb << "]" << endl);
rb = read_register(rn) + rb;
rc = read_register(rd);
#ifndef UNSAFE_OPTIMIZATIONS
ra = read16(rb & (~1u));
#else
ra = read16(rb);
#endif
if(rb & 1)
{
ra &= 0x00FF;
@ -2298,7 +2308,11 @@ int Thumbulator::execute()
DO_DISS(statusMsg << "strb r" << dec << rd << ",[r" << dec << rn << ",r" << rm << "]" << endl);
rb = read_register(rn) + read_register(rm);
rc = read_register(rd);
#ifndef UNSAFE_OPTIMIZATIONS
ra = read16(rb & (~1u));
#else
ra = read16(rb);
#endif
if(rb & 1)
{
ra &= 0x00FF;