gsplus/src/debug_shell.re2c

/*
 * requires re2c (http://re2c.org)
 *
 */

#include <stdio.h>
#include <stdarg.h>
#include <ctype.h>
#include <string.h>

#include <unistd.h>
#include <signal.h>

#include "defc.h"
#include "disasm.h"




extern int g_fullscreen;
extern int g_config_control_panel;
extern Engine_reg engine;
extern int halt_sim;


int g_num_mp_breakpoints = 0;
word32 g_mp_breakpoints[MAX_BREAK_POINTS];

int g_num_bp_breakpoints = 0;
word32 g_bp_breakpoints[MAX_BREAK_POINTS];

int g_dbg_shell = 0;
int g_stepping = 0;

word32 g_abort_address = 0;
word32 g_abort_value = 0;
word32 g_abort_bytes = 0;


/*
 * todo 
 * - tool break support
 * - gs/os break support
 * - p8 break support
 * - nifty list data files
 * - gsbug template files
 * - r -> run to next rts/rtl
 * - n -> step over jsl/jsr [ temporary breakpoints? ]
 * - ! -> mini assembler
 * - option to drop into debug shell on BRK command
 */


word32 do_hexdump(word32 address, int lines) {
	static char hex[] = "0123456789abcdef";

	char buffer1[64];
	char buffer2[20];
	int i;

	while (--lines) {
		char *cp = buffer1;
		for (i = 0; i < 16; ++i) {
			uint8_t c = get_memory_c(address + i, 0);
			*cp++ = hex[c >> 4];
			*cp++ = hex[c & 0x0f];
			*cp++ = ' ';
			if (i == 7) *cp++ = ' ';

			buffer2[i] = (c < 0x80) && isprint(c) ? c : '.';
		}
		*cp = 0;
		buffer2[16] = 0;
		printf("%02x/%04x: %s  %s\n",
			address >> 16, address & 0xffff,
			buffer1, buffer2
			);
		address += 16;
		address &= 0xffffff;
	}

	return address;
}

word32 do_list(word32 address, int *psr_ptr, int lines) {

	char buffer[32];
	int psr = *psr_ptr;
	unsigned opcode;
	unsigned dtype;
	unsigned operand;
	word32 pc;
	int i;
	int args;

	while (lines--) {
		pc = address;

		opcode = get_memory_c(address++, 0) & 0xff;
		dtype = disasm_types[opcode];
		args = dtype >> 8;

		switch (args) {
			case 4:
				args = psr & 0x20 ? 1 : 2;
				break;
			case 5:
				args = psr & 0x10 ? 1 : 2;
				break;
		}
		operand = 0;
		switch(args) {
			case 1:
				operand = get_memory_c(address, 0);
				break;
			case 2:
				operand = get_memory16_c(address, 0);
				break;
			case 3:
				operand = get_memory24_c(address, 0);
				break;
		}
		address += args;
		buffer[0] = 0;

		switch(dtype & 0xff) {
			case ABS:
				sprintf(buffer, "$%04x", operand);
				break;
			case ABSX:
				sprintf(buffer, "$%04x,x", operand);
				break;
			case ABSY:
				sprintf(buffer, "$%04x,y", operand);
				break;

    case ABSIND:
      sprintf(buffer,"($%04x)",operand );
      break;
    case ABSXIND:
      sprintf(buffer,"($%04x,x)",operand );
      break;
    case IMPLY:
      break;
    case ACCUM:
      break;
    case IMMED:
      sprintf(buffer,"#$%0*x",args * 2, operand);
      break;
    case JUST8:
      sprintf(buffer,"$%02x",operand);
      break;
    case DLOC:
      sprintf(buffer,"$%02x",operand);
      break;
    case DLOCX:
      sprintf(buffer,"$%02x,x",operand);
      break;
    case DLOCY:
      sprintf(buffer,"$%02x,y",operand);
      break;
    case ABSLONG:
      sprintf(buffer,"$%06x",operand);
      break;
    case ABSLONGX:
      sprintf(buffer,"$%06x,x",operand);
      break;
    case DLOCIND:
      sprintf(buffer,"($%02x)",operand);
      break;
    case DLOCINDY:
      sprintf(buffer,"($%02x),y",operand);
      break;
    case DLOCXIND:
      sprintf(buffer,"($%02x,x)",operand);
      break;
    case DLOCBRAK:
      sprintf(buffer,"[$%02x]",operand);
      break;
    case DLOCBRAKY:
      sprintf(buffer,"[$%02x],y",operand);
      break;
    case DISP8:
      sprintf(buffer,"$%04x",
              (address+(int8_t)operand) & 0xffff);
      break;
    case DISP8S:
      sprintf(buffer,"$%02x,s",operand);
      break;
    case DISP8SINDY:
      sprintf(buffer,"($%02x,s),y",operand);
      break;
    case DISP16:
      sprintf(buffer,"$%04x",
              (address+(int16_t)(operand)) & 0xffff);
      break;
    case MVPMVN:
      sprintf(buffer,"$%02x,$%02x",operand & 0xff,operand >> 8);
      break;
    case SEPVAL:
    	psr |= operand;
      sprintf(buffer,"#$%02x",operand);
      break;
    case REPVAL:
    	psr &= ~operand;
      sprintf(buffer,"#$%02x",operand);
      break;
		}

		printf("%02x/%04x: %s %-10s",
			pc >> 16, pc & 0xffff,
			disasm_opcodes[opcode], buffer);

		printf("%02x", opcode);
		for(i = 0 ; i < args; ++i) {
			printf(" %02x", operand & 0xff);
			operand >>= 8;
		}
		fputc('\n', stdout);
	}
	*psr_ptr = psr;
	return address;
}


enum {
	REG_A,
	REG_B,
	REG_D,
	REG_E,
	REG_K,
	REG_MX,
	REG_P,
	REG_PC,
	REG_S,
	REG_X,
	REG_Y,
};

static word32 to_hex(const char *iter, const char *end) {
	word32 rv = 0;
	while(iter != end) {
		char c = *iter++;
		rv <<= 4;
		if (isdigit(c)) rv |= c - '0';
		else rv |= (c | 0x20) - 'a' + 10;
	}
	return rv;
}


/*!re2c
	re2c:define:YYCTYPE = char;
	re2c:yyfill:enable = 0;
	end = "\x00";
	x = [A-Fa-f0-9];
*/

static int do_assign(const char *cp, int reg) {

	word32 addr = 0;
	int has_bank = 0;
	const char *YYCURSOR = cp;
	const char *YYMARKER = NULL;

	/*!re2c

		* { return -1; }
		x{6} end {
			addr = to_hex(cp, cp + 6);
			has_bank = 1;
			goto next;
		}
		x{2} "/" x{4} end {
			addr = to_hex(cp, cp + 2) << 16;
			addr |= to_hex(cp + 3, cp + 7);
			has_bank = 1;
			goto next;
		} 
		x{4} end {
			addr = to_hex(cp, cp + 4);
			has_bank = 0;
			goto next;
		}
		"%"[01]{2} end {
			if (reg != REG_MX) return -1;
			if (cp[1] == '1') addr |= 0x20;
			if (cp[2] == '1') addr |= 0x10;
			goto next;
		}
	*/

next:

	if (has_bank && reg != REG_PC) return -1;

	switch(reg) {
		case REG_A: engine.acc = addr; break;
		case REG_X: engine.xreg = addr; break;
		case REG_Y: engine.yreg = addr; break;
		case REG_D: engine.direct = addr; break;
		case REG_S: engine.stack = addr; break;
		case REG_B: engine.dbank = addr & 0xff; break;

		case REG_E:
			engine.psr &= 0xff;
			if (addr) engine.psr |= 0x0100;
			break;

		case REG_K:
			addr = (addr & 0xff) << 16;
			engine.kpc = (engine.kpc & 0xffff) | addr;
			break;

		case REG_PC:
			if (!has_bank) addr |= (engine.kpc & 0xff0000);
			engine.kpc = addr;
			break;

		case REG_P:
			engine.psr &= ~0xff;
			engine.psr |= (addr & 0xff);
			break;

		case REG_MX:
			/* only 00, 10, 20, 30 are legal values */
			if ((addr | 0x30) != 0x30) return -1;
			engine.psr &= ~0x30;
			engine.psr |= addr;
			break;


	}

	/* fixup registers */
	if (engine.psr & 0x0100) {
		engine.psr |= 0x30;
		engine.stack = (engine.stack & 0xff) | 0x0100;
	}
	if (engine.psr & 0x10) {
		engine.xreg &= 0xff;
		engine.yreg &= 0xff;
	}
	return 0;
}

static word32 do_mem_assign(word32 addr, const char *cp) {
	/* "string" -> pokes ASCII chars */
	/* 'string' -> pokes ASCII chars | 0x80 */
	/* xx -> pokes hex byte */

	const char *YYCURSOR = cp;
	const char *YYMARKER = NULL;

	for(;;) {
		const char *start = YYCURSOR;
		/*!re2c
			end { return addr; }
			" " { continue; }
			* {
				fputs("Invalid data\n", stderr);
				return addr;
			}
			x{2} {
				set_memory_c(addr++, to_hex(start, YYCURSOR), 0);
				continue;
			}
			["] [^"\x00]* ["] {
				for(++start; start < YYCURSOR -1; ++start) {
					set_memory_c(addr++, *start, 0);				
				}
				continue;
			}
			['] [^'\x00]* ['] {
				for(++start; start < YYCURSOR -1; ++start) {
					set_memory_c(addr++, *start | 0x80, 0);				
				}
				continue;
			}

		*/
	}
}


static int addr_cmp(const void *a, const void *b) {
	word32 aa = *(const word32 *)a;
	word32 bb = *(const word32 *)b;

	return (int)aa - (int)bb;
}




#if 0
void show_bp() {
	int i;
	word32 addr;
	printf("Breakpoints:\n");
	for (i = 0; i < g_num_bp_breakpoints; ++i) {
		addr = g_bp_breakpoints[i];
		printf("%02x/%04x\n", addr >> 16, addr & 0xffff);
	}
}

void set_bp(word32 addr) {
	int i;

	for (i = 0; i < g_num_bp_breakpoints; ++i) {
		if (g_bp_breakpoints[i] == addr) break;
	}

	if (i < g_num_bp_breakpoints) return; /* already set */
	if (g_num_bp_breakpoints == MAX_BREAK_POINTS) {
		printf("Too many breakpoints.\n");
		return;
	}
	g_bp_breakpoints[g_num_bp_breakpoints++] = addr;


	qsort(g_bp_breakpoints, g_num_bp_breakpoints, sizeof(word32), addr_cmp);
	fixup_brks();
}

void delete_bp(word32 addr) {
	int i;

	for (i = 0; i < g_num_bp_breakpoints; ++i) {
		if (g_bp_breakpoints[i] == addr) break;
	}


	if (i == g_num_bp_breakpoints) return; /* not set */
	g_bp_breakpoints[i] = 0;
	g_bp_breakpoints[i] = g_bp_breakpoints[--g_num_bp_breakpoints]; 

	qsort(g_bp_breakpoints, g_num_bp_breakpoints, sizeof(word32), addr_cmp);
	fixup_brks();
}
#endif


void show_bp(int type) {
	int i;
	word32 addr;
	word32 *breakpoints;
	int num_breakpoints;

	switch(type) {
		case 'B':
			breakpoints = g_bp_breakpoints;
			num_breakpoints = g_num_bp_breakpoints;
			break;
		case 'M':
			breakpoints = g_mp_breakpoints;
			num_breakpoints = g_num_mp_breakpoints;
			break;
		default:
			fputs("Invalid breakpoint type\n", stderr);
			return;
	}

	fputs("Breakpoints:\n", stdout);
	for (i = 0; i < num_breakpoints; ++i) {
		addr = breakpoints[i];
		printf("%02x/%04x\n", addr >> 16, addr & 0xffff);
	}
}

void set_bp(int type, word32 addr) {
	int i;

	word32 *breakpoints;
	int num_breakpoints;

	switch(type) {
		case 'B':
			breakpoints = g_bp_breakpoints;
			num_breakpoints = g_num_bp_breakpoints;
			break;
		case 'M':
			breakpoints = g_mp_breakpoints;
			num_breakpoints = g_num_mp_breakpoints;
			break;
		default:
			fputs("Invalid breakpoint type\n", stderr);
			return;
	}

	for (i = 0; i < num_breakpoints; ++i) {
		if (breakpoints[i] == addr) break;
	}

	if (i < num_breakpoints) return; /* already set */
	if (num_breakpoints == MAX_BREAK_POINTS) {
		printf("Too many breakpoints.\n");
		return;
	}
	breakpoints[num_breakpoints++] = addr;

	switch(type) {
		case 'B': g_num_bp_breakpoints = num_breakpoints; break;
		case 'M': g_num_mp_breakpoints = num_breakpoints; break;
	}

	qsort(breakpoints, num_breakpoints, sizeof(word32), addr_cmp);
	fixup_brks();
}

void delete_bp(int type, word32 addr) {
	int i;

	word32 *breakpoints;
	int num_breakpoints;

	switch(type) {
		case 'B':
			breakpoints = g_bp_breakpoints;
			num_breakpoints = g_num_bp_breakpoints;
			break;
		case 'M':
			breakpoints = g_mp_breakpoints;
			num_breakpoints = g_num_mp_breakpoints;
			break;
		default:
			fputs("Invalid breakpoint type\n", stderr);
			return;
	}

	for (i = 0; i < num_breakpoints; ++i) {
		if (breakpoints[i] == addr) break;
	}

	switch(type) {
		case 'B': g_num_bp_breakpoints = num_breakpoints; break;
		case 'M': g_num_mp_breakpoints = num_breakpoints; break;
	}

	if (i == num_breakpoints) return; /* not set */
	breakpoints[i] = 0;
	breakpoints[i] = breakpoints[--num_breakpoints]; 

	qsort(breakpoints, num_breakpoints, sizeof(word32), addr_cmp);
	fixup_brks();


}



static int do_bp_mp_common(const char *cp, word32 default_bank, word32 *breakpoints, int *num_breakpoints) {
	/* bp
	 * bp [+-] address
	 */

	int i = 0;
	int plus = 1;
	word32 addr = 0;
	const char *YYCURSOR = NULL;
	const char *YYMARKER = NULL;

	while (*cp == ' ') ++cp;
	switch(*cp) {
		case '-': plus = 0;
		case '+':
			++cp;
			break;
	}

	if (*cp == 0) {
		/* just print them... */
		for (i = 0; i < *num_breakpoints; ++i) {
			addr = breakpoints[i];
			printf("%02x/%04x\n", addr >> 16, addr & 0xffff);
		}
		return 0;
	}

	YYCURSOR = cp;
	/*!re2c

		* { return -1; }
		x{6} end {
			addr = to_hex(cp, cp + 6);
			goto next;
		}
		x{2} "/" x{4} end {
			addr = to_hex(cp, cp + 2) << 16;
			addr |= to_hex(cp + 3, cp + 7);
			goto next;
		} 
		x{4} end {
			addr = to_hex(cp, cp + 4);
			addr |= default_bank;
			goto next;
		}
	*/

next:

	for (i = 0; i < *num_breakpoints; ++i) {
		if (breakpoints[i] == addr) break;
	}

	if (plus) {
		if (i < *num_breakpoints) return 0; /* already set */
		if (*num_breakpoints == MAX_BREAK_POINTS) {
			printf("Too many breakpoints.\n");
			return 0;
		}
		breakpoints[(*num_breakpoints)++] = addr;
	} else {
		if (i == *num_breakpoints) return 0; /* not set */
		breakpoints[i] = 0;
		breakpoints[i] = breakpoints[--(*num_breakpoints)]; 
	}

	/* sort */
	qsort(breakpoints, *num_breakpoints, sizeof(word32), addr_cmp);
	fixup_brks();

	return 0;
}

static int do_bp(const char *cp) {
	return do_bp_mp_common(cp, engine.kpc & 0xff0000,
		g_bp_breakpoints, &g_num_bp_breakpoints);
}

static int do_mp(const char *cp) {
	return do_bp_mp_common(cp, engine.dbank << 16,
		g_mp_breakpoints, &g_num_mp_breakpoints);
}

static void do_help(void) {

	fputs(
		"  *                Print registers\n"
		"  reg=value        Assign register (a,x,y,etc)\n"
		"  reset            Reset computer\n"
		"  quit             exit debugger\n"
		"  s                single step\n"
		"  g                go\n"
		"  bp               List PC breakpoints\n"
		"  mp               List memory breakpoints\n"
		"\n"
		"  [address];l      List\n"
		"  [address];h      Hexdump\n"
		"  [address];bp     Set PC breakpoint\n"
		"  [address];bp-    Remove PC breakpoint\n"
		"  [address];mp     Set memory breakpoint\n"
		"  [address];mp-    Remove memory breakpoint\n"
		"\n"
		"\n"
		"Address = 12/3456, 123456, or 1234\n",
		stdout);
}

static word32 g_prev_address = 0;

/* return -1 on error, 0 on success, 1 if debug shell should exit. */
static int parse_command(const char *cp) {

	const char *YYCURSOR = cp;
	const char *YYMARKER = NULL;
	const char *ptr = NULL;

	int addr = 0;
	int has_bank = 0;
	int has_addr = 0;

	/*!stags:re2c format = "const char *@@;\n"; */

	while (*cp == ' ') ++cp;

	/*!re2c

		_ = (" " | "\x00");

		* { --YYCURSOR; if (cp == YYCURSOR) goto command; return -1; }

		"a=" { return do_assign(YYCURSOR, REG_A); }
		"x=" { return do_assign(YYCURSOR, REG_X); }
		"y=" { return do_assign(YYCURSOR, REG_Y); }
		"d=" { return do_assign(YYCURSOR, REG_D); }
		"e=" { return do_assign(YYCURSOR, REG_E); }
		"s=" { return do_assign(YYCURSOR, REG_S); }
		"k=" { return do_assign(YYCURSOR, REG_K); }
		"b=" { return do_assign(YYCURSOR, REG_B); }
		"p=" { return do_assign(YYCURSOR, REG_P); }
		"pc=" { return do_assign(YYCURSOR, REG_PC); }
		"mx=" { return do_assign(YYCURSOR, REG_MX); }

		"bp" end { show_bp('B'); return 0; }
		"mp" end { show_bp('M'); return 0; }

		"*" end { show_regs(); return 0; }

		("q" | "quit" | "exit") end { return 'q'; }
		"reset" end { do_reset(); return 0; }
		("help" | "?") end { do_help(); return 0; }

		"pc" {
			addr = engine.kpc;
			has_addr = 1;
			has_bank = 1;
			goto indir;
		}
		"a" {
			addr = engine.acc;
			has_addr = 1;
			has_bank = 0;
			goto indir;
		}
		"x" {
			addr = engine.xreg;
			has_addr = 1;
			has_bank = 0;
			goto indir;
		}
		"y" {
			addr = engine.yreg;
			has_addr = 1;
			has_bank = 0;
			goto indir;
		}
		"s" {
			addr = engine.stack;
			has_addr = 1;
			has_bank = 1;
			goto indir;
		}
		"d" {
			addr = engine.dbank;
			has_addr = 1;
			has_bank = 1;
			goto indir;
		}

		x{6} {
			addr = to_hex(cp, cp + 6);
			has_bank = 1;
			has_addr = 1;
			goto indir;
		}
		x{2} "/" x{4} {
			addr = to_hex(cp, cp + 2) << 16;
			addr |= to_hex(cp + 3, cp + 7);
			has_bank = 1;
			has_addr = 1;
			goto indir;
		} 
		x{1,4} {
			addr = to_hex(cp, YYCURSOR);
			has_bank = 0;
			has_addr = 1;
			goto indir;
		}
	*/
indir:
	/* only gets here if address specified */
	for(;;) {
	/*!re2c
		"" { break; }
		"^" {
			/* 3-byte indirection */
			if (!has_bank) addr = (g_prev_address & 0xff0000) | addr;
			addr = get_memory24_c(addr, 0);
			has_bank = 1;
			continue; 
		}
		"@" {
			/* 2-byte indirection */
			/* 3-byte indirection */
			if (!has_bank) addr = (g_prev_address & 0xff0000) | addr;
			word32 b = addr & 0xff0000;
			addr = get_memory16_c(addr, 0) | b;
			has_bank = 1;
			continue; 
		}
	*/
	}

command:
	/*!re2c
		* { return  -1; }
		";l" end {

		":" {
			if (!has_addr) {
				addr = g_prev_address;
				has_bank = 1;
			}
			if (!has_bank) addr |= (g_prev_address & 0xff0000);
			g_prev_address = do_mem_assign(addr, YYCURSOR);
			return 0;
		}
			int psr = engine.psr;
			if (!has_addr) {
				addr = g_prev_address;
				if (!addr) {
					addr = engine.kpc;
					has_bank = 1;
				}
			}
			if (!has_bank) {
				addr |= (engine.kpc & 0xff0000);
			}
			g_prev_address = do_list(addr, &psr, 20);
			return 0;
		}
		";h" end {
			if (!has_addr) {
				addr = g_prev_address;
				has_bank = 1;
			}
			if (!has_bank) {
				addr |= (engine.dbank << 16);
			}
			g_prev_address = do_hexdump(addr, 20);
			return 0;
		}
		"g" end {
			/* GO! */
			if (has_addr) {
				if (!has_bank) addr |= (engine.kpc & 0xff0000);
				engine.kpc = addr;
			}
			g_stepping = 0;
			return 1;
		}
		"s" end {
			/* step */
			if (has_addr) {
				if (!has_bank) addr |= (engine.kpc & 0xff0000);
				engine.kpc = addr;
			}
			g_stepping = 1;
			return 1;
		}

		";bp" @ptr [+-]? end {
			char plus = *ptr;
			if (!has_addr && plus == 0) { show_bp('B'); return 0; }
			if (!has_addr) return -1;
			if (!has_bank) addr |= (engine.kpc & 0xff0000);
			if (plus == '-') delete_bp('B', addr);
			else set_bp('B', addr);
			return 0;
		}

		";mp" @ptr [+-]? end {
			char plus = *ptr;
			if (!has_addr && plus == 0) { show_bp('M'); return 0; }
			if (!has_addr) return -1;
			if (!has_bank) addr |= (engine.kpc & 0xff0000);
			if (plus == '-') delete_bp('M', addr);
			else set_bp('M', addr);
			return 0;
		}

	*/
}

char *readline(const char *prompt) {
	static char buffer[1024];
	fputs(prompt, stdout);
	fflush(stdout);

	for(;;) {
		int ok = read(STDIN_FILENO, buffer, sizeof(buffer)-1);
		if (ok < 0) {
			if (ok == EINTR) continue;
			return NULL;
		}
		if (ok == 0) return NULL;
		while (ok) {
			char c = buffer[ok-1];
			if (c == ' ' || c == '\r' || c == '\n') {
				--ok;
				continue;
			}
			break;
		}
		buffer[ok] = 0;

		return buffer;
	}
}

int debug_shell(int code) {
	int c;
	char *cp;

	int psr = engine.psr;


	/* todo -- only clear IF exit pc == entry pc ? */
	if (code == RET_BP) {
		engine.flags |= FLAG_IGNORE_BP;
		printf("Breakpoint hit:\n");
	}
	if (code == RET_MP) {
		engine.flags |= FLAG_IGNORE_MP;
		printf("Memory breakpoint hit\n");
		switch (g_abort_bytes) {
			case 1: g_abort_value &= 0xff; break;
			case 2: g_abort_value &= 0xffff; break;
			case 3: g_abort_value &= 0xffffff; break;
		} 
		printf("%06x: %0*x\n", g_abort_address, g_abort_bytes * 2, g_abort_value);
	}
	if (code == RET_BRK) {
		/* hit a BRK op */
	}
	if (code == RET_HALT) {
		/* halt_printf */
	}

	do_list(engine.kpc, &psr, 1);

	for(;;) {
		cp = readline("> ");
		if (!cp) return 0;
		if (!*cp) continue;
		c = parse_command(cp);
		if (c < 0) printf("error.\n");
		if (c == 'q') return 0;
		if (c == 1) return 1;
	}
}

static void do_sig_intr(int sig, siginfo_t *info, void *context) {
	set_halt(4);
}

/* also called by do_step */
void do_go()      {
  int ret;
  int ok;

  /* if -g flag, start with debug shell ... */
  if (isatty(STDIN_FILENO)) {
  	struct sigaction sa;
  	memset(&sa, 0, sizeof(sa));
  	sigemptyset(&sa.sa_mask);
  	sa.sa_flags = SA_SIGINFO;
  	sa.sa_sigaction = do_sig_intr;
  	sigaction(SIGINT, &sa, NULL);

  } else {
  	g_dbg_shell = 0;  	
  }

  g_config_control_panel = 1;
  if (g_dbg_shell) {
  	ok = debug_shell(0);
  	if (!ok) return;
  }

  g_config_control_panel = 0;
  clear_halt();

  for(;;) {

    ret = run_prog();
    if (ret || g_stepping) {
      g_config_control_panel = 1;
      ok = debug_shell(ret);
      if (!ok) return;
      g_config_control_panel = 0;
      halt_sim &= ~0x07; /* clear any pending control-Cs, etc. */
    }
  }
}

/* legacy */



void halt_printf(const char *fmt, ...)      {
  va_list args;

  va_start(args, fmt);
  vprintf(fmt, args);
  va_end(args);

  set_halt(1);
}

void halt2_printf(const char *fmt, ...)      {
  va_list args;

  va_start(args, fmt);
  vprintf(fmt, args);
  va_end(args);

  set_halt(2);
}