view debug.c @ 921:2be771c4dfbd

After reviewing the results of my test ROM again it seems pretty clear that the VBlank flag gets set at the same time as the vcounter changes
author Michael Pavone <pavone@retrodev.com>
date Tue, 26 Jan 2016 19:23:10 -0800
parents 38dca41f151d
children f33e8d88ab6f
line wrap: on
line source

#include "debug.h"
#include "blastem.h"
#include "68kinst.h"
#include <stdlib.h>
#include <string.h>
#ifndef _WIN32
#include <sys/select.h>
#endif
#include "render.h"
#include "util.h"
#include "terminal.h"

static bp_def * breakpoints = NULL;
static bp_def * zbreakpoints = NULL;
static uint32_t bp_index = 0;
static uint32_t zbp_index = 0;

bp_def ** find_breakpoint(bp_def ** cur, uint32_t address)
{
	while (*cur) {
		if ((*cur)->address == address) {
			break;
		}
		cur = &((*cur)->next);
	}
	return cur;
}

bp_def ** find_breakpoint_idx(bp_def ** cur, uint32_t index)
{
	while (*cur) {
		if ((*cur)->index == index) {
			break;
		}
		cur = &((*cur)->next);
	}
	return cur;
}

disp_def * displays = NULL;
disp_def * zdisplays = NULL;
uint32_t disp_index = 0;
uint32_t zdisp_index = 0;

void add_display(disp_def ** head, uint32_t *index, char format_char, char * param)
{
	disp_def * ndisp = malloc(sizeof(*ndisp));
	ndisp->format_char = format_char;
	ndisp->param = strdup(param);
	ndisp->next = *head;
	ndisp->index = *index++;
	*head = ndisp;
}

void remove_display(disp_def ** head, uint32_t index)
{
	while (*head) {
		if ((*head)->index == index) {
			disp_def * del_disp = *head;
			*head = del_disp->next;
			free(del_disp->param);
			free(del_disp);
		} else {
			head = &(*head)->next;
		}
	}
}

char * find_param(char * buf)
{
	for (; *buf; buf++) {
		if (*buf == ' ') {
			if (*(buf+1)) {
				return buf+1;
			}
		}
	}
	return NULL;
}

void strip_nl(char * buf)
{
	for(; *buf; buf++) {
		if (*buf == '\n') {
			*buf = 0;
			return;
		}
	}
}

void debugger_print(m68k_context *context, char format_char, char *param)
{
	uint32_t value;
	char format[8];
	strcpy(format, "%s: %d\n");
	switch (format_char)
	{
	case 'x':
	case 'X':
	case 'd':
	case 'c':
		format[5] = format_char;
		break;
	case '\0':
		break;
	default:
		fprintf(stderr, "Unrecognized format character: %c\n", format_char);
	}
	if (param[0] == 'd' && param[1] >= '0' && param[1] <= '7') {
		value = context->dregs[param[1]-'0'];
	} else if (param[0] == 'a' && param[1] >= '0' && param[1] <= '7') {
		value = context->aregs[param[1]-'0'];
	} else if (param[0] == 'S' && param[1] == 'R') {
		value = (context->status << 8);
		for (int flag = 0; flag < 5; flag++) {
			value |= context->flags[flag] << (4-flag);
		}
	} else if(param[0] == 'c') {
		value = context->current_cycle;
	} else if ((param[0] == '0' && param[1] == 'x') || param[0] == '$') {
		uint32_t p_addr = strtol(param+(param[0] == '0' ? 2 : 1), NULL, 16);
		if ((p_addr & 0xFFFFFF) == 0xC00004) {
			genesis_context * gen = context->system;
			value = vdp_hv_counter_read(gen->vdp);
		} else {
			uint16_t *word = get_native_pointer(p_addr & 0xFFFFFE, (void **)context->mem_pointers, &context->options->gen);
			value = *word;
		}
	} else {
		fprintf(stderr, "Unrecognized parameter to p: %s\n", param);
		return;
	}
	printf(format, param, value);
}

#ifndef NO_Z80

void zdebugger_print(z80_context * context, char format_char, char * param)
{
	uint32_t value;
	char format[8];
	strcpy(format, "%s: %d\n");
	switch (format_char)
	{
	case 'x':
	case 'X':
	case 'd':
	case 'c':
		format[5] = format_char;
		break;
	case '\0':
		break;
	default:
		fprintf(stderr, "Unrecognized format character: %c\n", format_char);
	}
	switch (param[0])
	{
	case 'a':
		if (param[1] == 'f') {
			if(param[2] == '\'') {
				value = context->alt_regs[Z80_A] << 8;
				value |= context->alt_flags[ZF_S] << 7;
				value |= context->alt_flags[ZF_Z] << 6;
				value |= context->alt_flags[ZF_H] << 4;
				value |= context->alt_flags[ZF_PV] << 2;
				value |= context->alt_flags[ZF_N] << 1;
				value |= context->alt_flags[ZF_C];
			} else {
				value = context->regs[Z80_A] << 8;
				value |= context->flags[ZF_S] << 7;
				value |= context->flags[ZF_Z] << 6;
				value |= context->flags[ZF_H] << 4;
				value |= context->flags[ZF_PV] << 2;
				value |= context->flags[ZF_N] << 1;
				value |= context->flags[ZF_C];
			}
		} else if(param[1] == '\'') {
			value = context->alt_regs[Z80_A];
		} else {
			value = context->regs[Z80_A];
		}
		break;
	case 'b':
		if (param[1] == 'c') {
			if(param[2] == '\'') {
				value = context->alt_regs[Z80_B] << 8;
				value |= context->alt_regs[Z80_C];
			} else {
				value = context->regs[Z80_B] << 8;
				value |= context->regs[Z80_C];
			}
		} else if(param[1] == '\'') {
			value = context->alt_regs[Z80_B];
		} else if(param[1] == 'a') {
			value = context->bank_reg << 15;
		} else {
			value = context->regs[Z80_B];
		}
		break;
	case 'c':
		if(param[1] == '\'') {
			value = context->alt_regs[Z80_C];
		} else if(param[1] == 'y') {
			value = context->current_cycle;
		} else {
			value = context->regs[Z80_C];
		}
		break;
	case 'd':
		if (param[1] == 'e') {
			if(param[2] == '\'') {
				value = context->alt_regs[Z80_D] << 8;
				value |= context->alt_regs[Z80_E];
			} else {
				value = context->regs[Z80_D] << 8;
				value |= context->regs[Z80_E];
			}
		} else if(param[1] == '\'') {
			value = context->alt_regs[Z80_D];
		} else {
			value = context->regs[Z80_D];
		}
		break;
	case 'e':
		if(param[1] == '\'') {
			value = context->alt_regs[Z80_E];
		} else {
			value = context->regs[Z80_E];
		}
		break;
	case 'f':
		if(param[2] == '\'') {
			value = context->alt_flags[ZF_S] << 7;
			value |= context->alt_flags[ZF_Z] << 6;
			value |= context->alt_flags[ZF_H] << 4;
			value |= context->alt_flags[ZF_PV] << 2;
			value |= context->alt_flags[ZF_N] << 1;
			value |= context->alt_flags[ZF_C];
		} else {
			value = context->flags[ZF_S] << 7;
			value |= context->flags[ZF_Z] << 6;
			value |= context->flags[ZF_H] << 4;
			value |= context->flags[ZF_PV] << 2;
			value |= context->flags[ZF_N] << 1;
			value |= context->flags[ZF_C];
		}
		break;
	case 'h':
		if (param[1] == 'l') {
			if(param[2] == '\'') {
				value = context->alt_regs[Z80_H] << 8;
				value |= context->alt_regs[Z80_L];
			} else {
				value = context->regs[Z80_H] << 8;
				value |= context->regs[Z80_L];
			}
		} else if(param[1] == '\'') {
			value = context->alt_regs[Z80_H];
		} else {
			value = context->regs[Z80_H];
		}
		break;
	case 'l':
		if(param[1] == '\'') {
			value = context->alt_regs[Z80_L];
		} else {
			value = context->regs[Z80_L];
		}
		break;
	case 'i':
		if(param[1] == 'x') {
			if (param[2] == 'h') {
				value = context->regs[Z80_IXH];
			} else if(param[2] == 'l') {
				value = context->regs[Z80_IXL];
			} else {
				value = context->regs[Z80_IXH] << 8;
				value |= context->regs[Z80_IXL];
			}
		} else if(param[1] == 'y') {
			if (param[2] == 'h') {
				value = context->regs[Z80_IYH];
			} else if(param[2] == 'l') {
				value = context->regs[Z80_IYL];
			} else {
				value = context->regs[Z80_IYH] << 8;
				value |= context->regs[Z80_IYL];
			}
		} else if(param[1] == 'n') {
			value = context->int_cycle;
		} else if(param[1] == 'f' && param[2] == 'f' && param[3] == '1') {
			value = context->iff1;
		} else if(param[1] == 'f' && param[2] == 'f' && param[3] == '2') {
			value = context->iff2;
		} else {
			value = context->im;
		}
		break;
	case 's':
		if (param[1] == 'p') {
			value = context->sp;
		}
		break;
	case '0':
		if (param[1] == 'x') {
			uint16_t p_addr = strtol(param+2, NULL, 16);
			if (p_addr < 0x4000) {
				value = z80_ram[p_addr & 0x1FFF];
			} else if(p_addr >= 0x8000) {
				uint32_t v_addr = context->bank_reg << 15;
				v_addr += p_addr & 0x7FFF;
				if (v_addr < 0x400000) {
					value = cart[v_addr/2];
				} else if(v_addr > 0xE00000) {
					value = ram[(v_addr & 0xFFFF)/2];
				}
				if (v_addr & 1) {
					value &= 0xFF;
				} else {
					value >>= 8;
				}
			}
		}
		break;
	}
	printf(format, param, value);
}

z80_context * zdebugger(z80_context * context, uint16_t address)
{
	static char last_cmd[1024];
	char input_buf[1024];
	static uint16_t branch_t;
	static uint16_t branch_f;
	z80inst inst;
	init_terminal();
	//Check if this is a user set breakpoint, or just a temporary one
	bp_def ** this_bp = find_breakpoint(&zbreakpoints, address);
	if (*this_bp) {
		printf("Z80 Breakpoint %d hit\n", (*this_bp)->index);
	} else {
		zremove_breakpoint(context, address);
	}
	uint8_t * pc;
	if (address < 0x4000) {
		pc = z80_ram + (address & 0x1FFF);
	} else if (address >= 0x8000) {
		if (context->bank_reg < (0x400000 >> 15)) {
			fatal_error("Entered Z80 debugger in banked memory address %X, which is not yet supported\n", address);
		} else {
			fatal_error("Entered Z80 debugger in banked memory address %X, but the bank is not pointed to a cartridge address\n", address);
		}
	} else {
		fatal_error("Entered Z80 debugger at address %X\n", address);
	}
	for (disp_def * cur = zdisplays; cur; cur = cur->next) {
		zdebugger_print(context, cur->format_char, cur->param);
	}
	uint8_t * after_pc = z80_decode(pc, &inst);
	z80_disasm(&inst, input_buf, address);
	printf("%X:\t%s\n", address, input_buf);
	uint16_t after = address + (after_pc-pc);
	int debugging = 1;
	while(debugging) {
		fputs(">", stdout);
		if (!fgets(input_buf, sizeof(input_buf), stdin)) {
			fputs("fgets failed", stderr);
			break;
		}
		strip_nl(input_buf);
		//hitting enter repeats last command
		if (input_buf[0]) {
			strcpy(last_cmd, input_buf);
		} else {
			strcpy(input_buf, last_cmd);
		}
		char * param;
		char format[8];
		uint32_t value;
		bp_def * new_bp;
		switch(input_buf[0])
		{
			case 'a':
				param = find_param(input_buf);
				if (!param) {
					fputs("a command requires a parameter\n", stderr);
					break;
				}
				value = strtol(param, NULL, 16);
				zinsert_breakpoint(context, value, (uint8_t *)zdebugger);
				debugging = 0;
				break;
			case 'b':
				param = find_param(input_buf);
				if (!param) {
					fputs("b command requires a parameter\n", stderr);
					break;
				}
				value = strtol(param, NULL, 16);
				zinsert_breakpoint(context, value, (uint8_t *)zdebugger);
				new_bp = malloc(sizeof(bp_def));
				new_bp->next = zbreakpoints;
				new_bp->address = value;
				new_bp->index = zbp_index++;
				new_bp->commands = NULL;
				zbreakpoints = new_bp;
				printf("Z80 Breakpoint %d set at %X\n", new_bp->index, value);
				break;
			case 'c':
				puts("Continuing");
				debugging = 0;
				break;
			case 'd':
				if (input_buf[1] == 'i') {
					char format_char = 0;
					for(int i = 2; input_buf[i] != 0 && input_buf[i] != ' '; i++) {
						if (input_buf[i] == '/') {
							format_char = input_buf[i+1];
							break;
						}
					}
					param = find_param(input_buf);
					if (!param) {
						fputs("display command requires a parameter\n", stderr);
						break;
					}
					zdebugger_print(context, format_char, param);
					add_display(&zdisplays, &zdisp_index, format_char, param);
				} else if (input_buf[1] == 'e' || input_buf[1] == ' ') {
					param = find_param(input_buf);
					if (!param) {
						fputs("delete command requires a parameter\n", stderr);
						break;
					}
					if (param[0] >= '0' && param[0] <= '9') {
						value = atoi(param);
						this_bp = find_breakpoint_idx(&zbreakpoints, value);
						if (!*this_bp) {
							fprintf(stderr, "Breakpoint %d does not exist\n", value);
							break;
						}
						new_bp = *this_bp;
						zremove_breakpoint(context, new_bp->address);
						*this_bp = new_bp->next;
						free(new_bp);
					} else if (param[0] == 'd') {
						param = find_param(param);
						if (!param) {
							fputs("delete display command requires a parameter\n", stderr);
							break;
						}
						remove_display(&zdisplays, atoi(param));
					}
				}
				break;
			case 'n':
				//TODO: Handle conditional branch instructions
				if (inst.op == Z80_JP) {
					if (inst.addr_mode == Z80_IMMED) {
						after = inst.immed;
					} else if (inst.ea_reg == Z80_HL) {
						after = context->regs[Z80_H] << 8 | context->regs[Z80_L];
					} else if (inst.ea_reg == Z80_IX) {
						after = context->regs[Z80_IXH] << 8 | context->regs[Z80_IXL];
					} else if (inst.ea_reg == Z80_IY) {
						after = context->regs[Z80_IYH] << 8 | context->regs[Z80_IYL];
					}
				} else if(inst.op == Z80_JR) {
					after += inst.immed;
				} else if(inst.op == Z80_RET) {
					if (context->sp < 0x4000) {
						after = z80_ram[context->sp & 0x1FFF] | z80_ram[(context->sp+1) & 0x1FFF] << 8;
					}
				}
				zinsert_breakpoint(context, after, (uint8_t *)zdebugger);
				debugging = 0;
				break;
			case 'p':
				param = find_param(input_buf);
				if (!param) {
					fputs("p command requires a parameter\n", stderr);
					break;
				}
				zdebugger_print(context, input_buf[1] == '/' ? input_buf[2] : 0, param);
				break;
			case 'q':
				puts("Quitting");
				exit(0);
				break;
			case 's': {
				param = find_param(input_buf);
				if (!param) {
					fputs("s command requires a file name\n", stderr);
					break;
				}
				FILE * f = fopen(param, "wb");
				if (f) {
					if(fwrite(z80_ram, 1, sizeof(z80_ram), f) != sizeof(z80_ram)) {
						fputs("Error writing file\n", stderr);
					}
					fclose(f);
				} else {
					fprintf(stderr, "Could not open %s for writing\n", param);
				}
				break;
			}
			default:
				fprintf(stderr, "Unrecognized debugger command %s\n", input_buf);
				break;
		}
	}
	return context;
}

#endif

static uint32_t branch_t;
static uint32_t branch_f;

int run_debugger_command(m68k_context *context, char *input_buf, m68kinst inst, uint32_t after)
{
	char * param;
	char format_char;
	uint32_t value;
	bp_def *new_bp, **this_bp;
	switch(input_buf[0])
	{
		case 'c':
			if (input_buf[1] == 0 || input_buf[1] == 'o' && input_buf[2] == 'n')
			{
				puts("Continuing");
				return 0;
			} else if (input_buf[1] == 'o' && input_buf[2] == 'm') {
				param = find_param(input_buf);
				if (!param) {
					fputs("com command requires a parameter\n", stderr);
					break;
				}
				bp_def **target = find_breakpoint_idx(&breakpoints, atoi(param));
				if (!target) {
					fprintf(stderr, "Breakpoint %s does not exist!\n", param);
					break;
				}
				printf("Enter commands for breakpoing %d, type end when done\n", atoi(param));
				char cmd_buf[1024];
				char *commands = NULL;
				for (;;)
				{
					fputs(">>", stdout);
					fflush(stdout);
					fgets(cmd_buf, sizeof(cmd_buf), stdin);
					if (strcmp(cmd_buf, "end\n")) {
						if (commands) {
							char *tmp = commands;
							commands = alloc_concat(commands, cmd_buf);
							free(tmp);
						} else {
							commands = strdup(cmd_buf);
						}
					} else {
						break;
					}
				}
				(*target)->commands = commands;
			} else {
			}
		case 'b':
			if (input_buf[1] == 't') {
				uint32_t stack = context->aregs[7];
				if (stack >= 0xE00000) {
					stack &= 0xFFFF;
					uint8_t non_adr_count = 0;
					do {
						uint32_t bt_address = ram[stack/2] << 16 | ram[stack/2+1];
						bt_address = get_instruction_start(context->native_code_map, bt_address - 2);
						if (bt_address) {
							stack += 4;
							non_adr_count = 0;
							uint16_t *bt_pc = NULL;
							if (bt_address < 0x400000) {
								bt_pc = cart + bt_address/2;
							} else if(bt_address > 0xE00000) {
								bt_pc = ram + (bt_address & 0xFFFF)/2;
							}
							m68k_decode(bt_pc, &inst, bt_address);
							m68k_disasm(&inst, input_buf);
							printf("%X: %s\n", bt_address, input_buf);
						} else {
							//non-return address value on stack can be word wide
							stack += 2;
							non_adr_count++;
						}
						stack &= 0xFFFF;
					} while (stack && non_adr_count < 6);
				}
			} else {
				param = find_param(input_buf);
				if (!param) {
					fputs("b command requires a parameter\n", stderr);
					break;
				}
				value = strtol(param, NULL, 16);
				insert_breakpoint(context, value, (uint8_t *)debugger);
				new_bp = malloc(sizeof(bp_def));
				new_bp->next = breakpoints;
				new_bp->address = value;
				new_bp->index = bp_index++;
				new_bp->commands = NULL;
				breakpoints = new_bp;
				printf("68K Breakpoint %d set at %X\n", new_bp->index, value);
			}
			break;
		case 'a':
			param = find_param(input_buf);
			if (!param) {
				fputs("a command requires a parameter\n", stderr);
				break;
			}
			value = strtol(param, NULL, 16);
			insert_breakpoint(context, value, (uint8_t *)debugger);
			return 0;
		case 'd':
			if (input_buf[1] == 'i') {
				format_char = 0;
				for(int i = 2; input_buf[i] != 0 && input_buf[i] != ' '; i++) {
					if (input_buf[i] == '/') {
						format_char = input_buf[i+1];
						break;
					}
				}
				param = find_param(input_buf);
				if (!param) {
					fputs("display command requires a parameter\n", stderr);
					break;
				}
				debugger_print(context, format_char, param);
				add_display(&displays, &disp_index, format_char, param);
			} else {
				param = find_param(input_buf);
				if (!param) {
					fputs("d command requires a parameter\n", stderr);
					break;
				}
				value = atoi(param);
				this_bp = find_breakpoint_idx(&breakpoints, value);
				if (!*this_bp) {
					fprintf(stderr, "Breakpoint %d does not exist\n", value);
					break;
				}
				new_bp = *this_bp;
				*this_bp = (*this_bp)->next;
				if (new_bp->commands) {
					free(new_bp->commands);
				}
				free(new_bp);
			}
			break;
		case 'p':
			format_char = 0;
			for(int i = 1; input_buf[i] != 0 && input_buf[i] != ' '; i++) {
				if (input_buf[i] == '/') {
					format_char = input_buf[i+1];
					break;
				}
			}
			param = find_param(input_buf);
			if (!param) {
				fputs("p command requires a parameter\n", stderr);
				break;
			}
			debugger_print(context, format_char, param);
			break;
		case 'n':
			if (inst.op == M68K_RTS) {
				after = (read_dma_value(context->aregs[7]/2) << 16) | read_dma_value(context->aregs[7]/2 + 1);
			} else if (inst.op == M68K_RTE || inst.op == M68K_RTR) {
				after = (read_dma_value((context->aregs[7]+2)/2) << 16) | read_dma_value((context->aregs[7]+2)/2 + 1);
			} else if(m68k_is_noncall_branch(&inst)) {
				if (inst.op == M68K_BCC && inst.extra.cond != COND_TRUE) {
					branch_f = after;
					branch_t = m68k_branch_target(&inst, context->dregs, context->aregs);
					insert_breakpoint(context, branch_t, (uint8_t *)debugger);
				} else if(inst.op == M68K_DBCC) {
					if ( inst.extra.cond == COND_FALSE) {
						if (context->dregs[inst.dst.params.regs.pri] & 0xFFFF) {
							after = m68k_branch_target(&inst, context->dregs, context->aregs);
						}
					} else {
						branch_t = after;
						branch_f = m68k_branch_target(&inst, context->dregs, context->aregs);
						insert_breakpoint(context, branch_f, (uint8_t *)debugger);
					}
				} else {
					after = m68k_branch_target(&inst, context->dregs, context->aregs);
				}
			}
			insert_breakpoint(context, after, (uint8_t *)debugger);
			return 0;
		case 'o':
			if (inst.op == M68K_RTS) {
				after = (read_dma_value(context->aregs[7]/2) << 16) | read_dma_value(context->aregs[7]/2 + 1);
			} else if (inst.op == M68K_RTE || inst.op == M68K_RTR) {
				after = (read_dma_value((context->aregs[7]+2)/2) << 16) | read_dma_value((context->aregs[7]+2)/2 + 1);
			} else if(m68k_is_noncall_branch(&inst)) {
				if (inst.op == M68K_BCC && inst.extra.cond != COND_TRUE) {
					branch_t = m68k_branch_target(&inst, context->dregs, context->aregs)  & 0xFFFFFF;
					if (branch_t < after) {
							branch_t = 0;
					} else {
						branch_f = after;
						insert_breakpoint(context, branch_t, (uint8_t *)debugger);
					}
				} else if(inst.op == M68K_DBCC) {
					uint32_t target = m68k_branch_target(&inst, context->dregs, context->aregs)  & 0xFFFFFF;
					if (target > after) {
						if (inst.extra.cond == COND_FALSE) {
							after = target;
						} else {
							branch_f = target;
							branch_t = after;
							insert_breakpoint(context, branch_f, (uint8_t *)debugger);
						}
					}
				} else {
					after = m68k_branch_target(&inst, context->dregs, context->aregs) & 0xFFFFFF;
				}
			}
			insert_breakpoint(context, after, (uint8_t *)debugger);
			return 0;
		case 's':
			if (inst.op == M68K_RTS) {
				after = (read_dma_value(context->aregs[7]/2) << 16) | read_dma_value(context->aregs[7]/2 + 1);
			} else if (inst.op == M68K_RTE || inst.op == M68K_RTR) {
				after = (read_dma_value((context->aregs[7]+2)/2) << 16) | read_dma_value((context->aregs[7]+2)/2 + 1);
			} else if(m68k_is_branch(&inst)) {
				if (inst.op == M68K_BCC && inst.extra.cond != COND_TRUE) {
					branch_f = after;
					branch_t = m68k_branch_target(&inst, context->dregs, context->aregs) & 0xFFFFFF;
					insert_breakpoint(context, branch_t, (uint8_t *)debugger);
				} else if(inst.op == M68K_DBCC && inst.extra.cond != COND_FALSE) {
					branch_t = after;
					branch_f = m68k_branch_target(&inst, context->dregs, context->aregs) & 0xFFFFFF;
					insert_breakpoint(context, branch_f, (uint8_t *)debugger);
				} else {
					after = m68k_branch_target(&inst, context->dregs, context->aregs) & 0xFFFFFF;
				}
			}
			insert_breakpoint(context, after, (uint8_t *)debugger);
			return 0;
		case 'v': {
			genesis_context * gen = context->system;
			//VDP debug commands
			switch(input_buf[1])
			{
			case 's':
				vdp_print_sprite_table(gen->vdp);
				break;
			case 'r':
				vdp_print_reg_explain(gen->vdp);
				break;
			}
			break;
		}
		case 'y': {
			genesis_context * gen = context->system;
			//YM-2612 debug commands
			switch(input_buf[1])
			{
			case 'c':
				if (input_buf[2] == ' ') {
					int channel = atoi(input_buf+3)-1;
					ym_print_channel_info(gen->ym, channel);
				} else {
					for (int i = 0; i < 6; i++) {
						ym_print_channel_info(gen->ym, i);
					}
				}
			}
			break;
		}
#ifndef NO_Z80
		case 'z': {
			genesis_context * gen = context->system;
			//Z80 debug commands
			switch(input_buf[1])
			{
			case 'b':
				param = find_param(input_buf);
				if (!param) {
					fputs("zb command requires a parameter\n", stderr);
					break;
				}
				value = strtol(param, NULL, 16);
				zinsert_breakpoint(gen->z80, value, (uint8_t *)zdebugger);
				new_bp = malloc(sizeof(bp_def));
				new_bp->next = zbreakpoints;
				new_bp->address = value;
				new_bp->index = zbp_index++;
				zbreakpoints = new_bp;
				printf("Z80 Breakpoint %d set at %X\n", new_bp->index, value);
				break;
			case 'p':
				param = find_param(input_buf);
				if (!param) {
					fputs("zp command requires a parameter\n", stderr);
					break;
				}
				zdebugger_print(gen->z80, input_buf[2] == '/' ? input_buf[3] : 0, param);
			}
			break;
		}
#endif
		case 'q':
			puts("Quitting");
			exit(0);
			break;
		default:
			fprintf(stderr, "Unrecognized debugger command %s\n", input_buf);
			break;
	}
	return 1;
}


m68k_context * debugger(m68k_context * context, uint32_t address)
{
	static char last_cmd[1024];
	char input_buf[1024];
	m68kinst inst;

	init_terminal();

	sync_components(context, 0);
	//probably not necessary, but let's play it safe
	address &= 0xFFFFFF;
	if (address == branch_t) {
		bp_def ** f_bp = find_breakpoint(&breakpoints, branch_f);
		if (!*f_bp) {
			remove_breakpoint(context, branch_f);
		}
		branch_t = branch_f = 0;
	} else if(address == branch_f) {
		bp_def ** t_bp = find_breakpoint(&breakpoints, branch_t);
		if (!*t_bp) {
			remove_breakpoint(context, branch_t);
		}
		branch_t = branch_f = 0;
	}

	uint16_t * pc;
	if (address < 0x400000) {
		pc = cart + address/2;
	} else if(address > 0xE00000) {
		pc = ram + (address & 0xFFFF)/2;
	} else {
		fatal_error("Entered 68K debugger at address %X\n", address);
	}
	uint16_t * after_pc = m68k_decode(pc, &inst, address);
	uint32_t after = address + (after_pc-pc)*2;
	int debugging = 1;
	//Check if this is a user set breakpoint, or just a temporary one
	bp_def ** this_bp = find_breakpoint(&breakpoints, address);
	if (*this_bp) {

		if ((*this_bp)->commands)
		{
			char *commands = strdup((*this_bp)->commands);
			char *copy = commands;

			while (debugging && *commands)
			{
				char *cmd = commands;
				strip_nl(cmd);
				commands += strlen(cmd) + 1;
				debugging = run_debugger_command(context, cmd, inst, after);
			}
			free(copy);
		}
		if (debugging) {
			printf("68K Breakpoint %d hit\n", (*this_bp)->index);
		} else {
			return context;
		}
	} else {
		remove_breakpoint(context, address);
	}
	for (disp_def * cur = displays; cur; cur = cur->next) {
		debugger_print(context, cur->format_char, cur->param);
	}
	m68k_disasm(&inst, input_buf);
	printf("%X: %s\n", address, input_buf);
#ifdef _WIN32
#define prompt 1
#else
	int prompt = 1;
	fd_set read_fds;
	FD_ZERO(&read_fds);
	struct timeval timeout;
#endif
	while (debugging) {
		if (prompt) {
			fputs(">", stdout);
			fflush(stdout);
		}
		process_events();
#ifndef _WIN32
		timeout.tv_sec = 0;
		timeout.tv_usec = 16667;
		FD_SET(fileno(stdin), &read_fds);
		if(select(fileno(stdin) + 1, &read_fds, NULL, NULL, &timeout) < 1) {
			prompt = 0;
			continue;
		} else {
			prompt = 1;
		}
#endif
		if (!fgets(input_buf, sizeof(input_buf), stdin)) {
			fputs("fgets failed", stderr);
			break;
		}
		strip_nl(input_buf);
		//hitting enter repeats last command
		if (input_buf[0]) {
			strcpy(last_cmd, input_buf);
		} else {
			strcpy(input_buf, last_cmd);
		}
		debugging = run_debugger_command(context, input_buf, inst, after);
	}
	return context;
}