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arm7: - Improved LDM/STM unaligned word access in THUMB mode. [Tim Schuerewegen]

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-Fixed LDM unaligned read in THUMB mode.
This commit is contained in:
Miodrag Milanovic 2011-01-29 10:23:02 +00:00
parent ae05d4a989
commit 82263d0988
1 changed files with 10 additions and 3 deletions
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13
src/emu/cpu/arm7/arm7exec.c
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@ -943,7 +943,14 @@
UINT32 ld_st_address;
rd = (insn & THUMB_MULTLS_BASE) >> THUMB_MULTLS_BASE_SHIFT;
ld_st_address = GET_REGISTER(cpustate, rd) & 0xfffffffc;
// "The address should normally be a word aligned quantity and non-word aligned addresses do not affect the instruction."
// "However, the bottom 2 bits of the address will appear on A[1:0] and might be interpreted by the memory system."
// GBA "BB Ball" performs an unaligned read with A[1:0] = 2 and expects A[1] not to be ignored [BP 800B90A,(R4&3)!=0]
// GBA "Gadget Racers" performs an unaligned read with A[1:0] = 1 and expects A[0] to be ignored [BP B72,(R0&3)!=0]
ld_st_address = GET_REGISTER(cpustate, rd);
if (insn & THUMB_MULTLS) /* Load */
{
@ -954,7 +961,7 @@
{
if (insn & (1 << offs))
{
SET_REGISTER(cpustate, offs, READ32(ld_st_address));
SET_REGISTER(cpustate, offs, READ32(ld_st_address & ~1));
ld_st_address += 4;
}
}
@ -968,7 +975,7 @@
{
if (insn & (1 << offs))
{
WRITE32(ld_st_address, GET_REGISTER(cpustate, offs));
WRITE32(ld_st_address & ~3, GET_REGISTER(cpustate, offs));
ld_st_address += 4;
}
}