//! 2.2.8.2 Execute a Single Step
//!
//! @param dnNrInstructions
//!
USBDM_GDI_API
DiReturnT DiExecSingleStep ( DiUInt32T dnNrInstructions ) {
USBDM_ErrorCode BDMrc;
Logging::print("DiExecSingleStep(%d)\n", dnNrInstructions);
CHECK_ERROR_STATE();
#if (TARGET == MC56F80xx)
BDMrc = DSC_TargetStepN(dnNrInstructions);
#else
if (dnNrInstructions>1) {
Logging::print("DiExecSingleStep() - Only a single step is supported!\n");
return setErrorState(DI_ERR_PARAM, ("Only a single step is allowed"));
}
BDMrc = USBDM_TargetStep();
#endif
if (BDMrc != BDM_RC_OK) {
return setErrorState(DI_ERR_NONFATAL, BDMrc);
}
return setErrorState(DI_OK);
}
//! 2.2.8.2 Execute a Single Step
//!
//! @param dnNrInstructions
//!
USBDM_GDI_DECLSPEC
DiReturnT DiExecSingleStep ( DiUInt32T dnNrInstructions ) {
LOGGING_Q;
log.print("(%d)\n", dnNrInstructions);
USBDM_ErrorCode BDMrc;
long unsigned ccrValue;
long unsigned pcValue;
unsigned char currentOpcode;
const int interruptMask = (1<<3);
const int tapOpcode = 0x84;
const int tpaOpcode = 0x85;
const int seiOpcode = 0x9B;
const int cliOpcode = 0x9A;
const int waitOpcode = 0x8F;
const int rtiOpcode = 0x80;
const int swiOpcode = 0x83;
const int stopOpcode = 0x8E;
CHECK_ERROR_STATE();
#if (TARGET == MC56F80xx)
BDMrc = DSC_TargetStepN(dnNrInstructions);
#else
if (dnNrInstructions>1) {
log.print("DiExecSingleStep() - Only a single step is supported!\n");
return setErrorState(DI_ERR_PARAM, ("Only a single step is allowed"));
}
/*
* Cases to consider when masking interrupts during step
*
* +--------+-----------+---------+-----------------------------------------------------+
* | Opcode | Initial I | Final I | Problem - action |
* +--------+-----------+---------+-----------------------------------------------------+
* | --- | 1 | X | None - no action (interrupts already masked) |
* +--------+-----------+---------+-----------------------------------------------------+
* | CLI | 0 | ? | It may be possible for an interrupt to occur, |
* | WAIT | | | setting I-flag which is then incorrectly cleared. |
* | STOP | | | (I don't think it applies to CLI but be safe.) |
* | SWI | | | - don't 'fix' CCR |
* +--------+-----------+---------+-----------------------------------------------------+
* | RTI | 0 | 1 | Contrived but possible situation. I flag |
* | | | | incorrectly cleared - don't 'fix' CCR |
* +--------+-----------+---------+-----------------------------------------------------+
* | SEI | 0 | 1 | The instruction may set I-flag which is then |
* | TAP | 0 | 1 | incorrectly cleared - don't 'fix' CCR |
* +--------+-----------+---------+-----------------------------------------------------+
* | TPA | 0 | X | The wrong value is transferred to A - fix A |
* +--------+-----------+---------+-----------------------------------------------------+
* | --- | 0 | 0 | CCR change - clear I-flag in new CCR |
* +--------+-----------+---------+-----------------------------------------------------+
*/
if (bdmOptions.maskInterrupts) {
log.print("DiExecSingleStep() - checking if interrupt masking needed\n");
USBDM_ReadReg(HCS08_RegCCR, &ccrValue);
if ((ccrValue&interruptMask) != 0) {
// Interrupts already masked - just step
BDMrc = USBDM_TargetStep();
}
else {
// Mask interrupts
log.print("DiExecSingleStep() - masking interrupts\n");
USBDM_WriteReg(HCS08_RegCCR, ccrValue|interruptMask);
// Get current instruction opcode
USBDM_ReadReg(HCS08_RegPC, &pcValue);
USBDM_ReadMemory(1,1,pcValue,¤tOpcode);
// Do a step
BDMrc = USBDM_TargetStep();
switch(currentOpcode) {
case cliOpcode :
case waitOpcode :
case seiOpcode :
case tapOpcode :
case rtiOpcode :
case swiOpcode : // Not ever stepped - treated as subroutine?
case stopOpcode :
log.print("DiExecSingleStep() - skipping CCR restore\n");
// Don't 'fix' CCR as updated by instruction or int ack
break;
case tpaOpcode :
// Fix A & CCR (clear I flag)
log.print("DiExecSingleStep() - fixing A & CCR reg\n");
USBDM_WriteReg(HCS08_RegA, ccrValue&~interruptMask);
USBDM_WriteReg(HCS08_RegCCR, ccrValue&~interruptMask);
break;
default :
// Fix CCR (clear I flag)
// Unmask interrupts
log.print("DiExecSingleStep() - fixing CCR reg\n");
USBDM_ReadReg(HCS08_RegCCR, &ccrValue);
USBDM_WriteReg(HCS08_RegCCR, ccrValue&~interruptMask);
break;
}
}
}
else
BDMrc = USBDM_TargetStep();
#endif
if (BDMrc != BDM_RC_OK) {
return setErrorState(DI_ERR_NONFATAL, BDMrc);
}
return setErrorState(DI_OK);
}
