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corrected 4d8c3c9

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the mistake was audible in the Mappy sound routine
This commit is contained in:
JetSetIlly 2024-04-10 20:26:26 +01:00
parent f491504d86
commit 1d40869a6d
1 changed files with 27 additions and 12 deletions
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39
hardware/memory/cartridge/arm/thumb.go
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@ -924,6 +924,17 @@ func (arm *ARM) decodeThumbHiRegisterOps(opcode uint16) decodeFunction {
}
}
// "7.6 Data Operations" in "ARM7TDMI-S Technical Reference Manual r4p3"
// - fillPipeline() will be called if necessary
var thumbMode bool
var newPC uint32
// if the low bit of the src register is set then the target is
// using the thumb instruction set and we can return almost
// immediately
thumbMode = arm.state.registers[srcReg]&0x01 == 0x01
switch arm.mmap.ARMArchitecture {
case architecture.ARMv7_M:
if opcode&0x0080 == 0x0080 {
@ -931,7 +942,7 @@ func (arm *ARM) decodeThumbHiRegisterOps(opcode uint16) decodeFunction {
nextPC := arm.state.registers[rPC] - 2
arm.state.registers[rLR] = nextPC | 0x01
}
arm.state.registers[rPC] = (arm.state.registers[srcReg] + 2) & 0xfffffffe
newPC = (arm.state.registers[srcReg] + 2) & 0xfffffffe
case architecture.ARM7TDMI:
// "ARM7TDMI Data Sheet" page 5-15:
@ -940,29 +951,33 @@ func (arm *ARM) decodeThumbHiRegisterOps(opcode uint16) decodeFunction {
// bit 0 cleared. Executing a BX PC in THUMB state from a non-word aligned address
// will result in unpredictable execution."
if srcReg == rPC {
arm.state.registers[rPC] = arm.state.registers[rPC] + 2
newPC = arm.state.registers[rPC] + 2
} else {
arm.state.registers[rPC] = (arm.state.registers[srcReg] + 2) & 0xfffffffe
newPC = (arm.state.registers[srcReg] + 2) & 0xfffffffe
}
}
// if the low bit of the src register is set then the target is
// using the thumb instruction set and we can return immediately
if arm.state.registers[srcReg]&0x01 == 0x01 {
// "7.6 Data Operations" in "ARM7TDMI-S Technical Reference Manual r4p3"
// - fillPipeline() will be called if necessary
return nil
}
// if the PC is now the same as the expected return address then the
// ARM program has ended and we can yield with the YieldProgramEnded
// type
if arm.state.registers[rPC] == arm.state.expectedReturnAddress {
//
// this has to come before the thumbMode check because for ROMs
// compiled for the Harmony architecture (ARM7TDMI), the return
// address will be a non-thumb address
if newPC == arm.state.expectedReturnAddress {
arm.state.yield.Type = coprocessor.YieldProgramEnded
arm.state.yield.Error = nil
return nil
}
// if we're still in thumb mode the instruction has ended
if thumbMode {
// "7.6 Data Operations" in "ARM7TDMI-S Technical Reference Manual r4p3"
// - fillPipeline() will be called if necessary
arm.state.registers[rPC] = newPC
return nil
}
// NOTE: the remainder of the instruction handles ARM interrupts.
// note that this hasn't been tested with ARMv7_M processor types.
// this type of processor does not have 32bit instructions so may