#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "xcpt.h"
#include "libsys.h"
#include "mips_dis.h"

#define DBG_PRINT_REG(tag_str, reg)			\
			dbg_puts(tag_str);				\
			dbg_print_word(reg);			\
			dbg_puts("   ");


#define DBG_PRINT_REG_CHG(tag_str, reg, chg_tag)			\
			dbg_puts(tag_str);				\
			dbg_print_word(reg);			\
			dbg_puts(chg_tag);				\
			dbg_puts("  ");

#define	MAX_USER_BP				16
#define	BP_MASK_ID				0x00FFF
#define	BP_MASK_TYPE			0xFF000

#define	BP_GET_ID(bp)			((bp >> 6) & 0xFFF)

#define	BP_USER_BASE			0x10000
#define	BP_USER(id)				(((BP_USER_BASE + id) << 6) | 0x0D)

#define	BP_MGMT_BASE_SS			0x20000
#define	BP_MGMT_SS(id)			(((BP_MGMT_BASE_SS + id) << 6) | 0x0D)

#define	BP_MGMT_BASE_RU			0x30000
#define	BP_MGMT_RU(id)			(((BP_MGMT_BASE_RU + id) << 6) | 0x0D)

static char g_buf[80];

enum
{
	STATE_INIT = 0,
	STATE_RUN,
	STATE_STEP_SINGLE,
	STATE_STEP_PROC,
	STATE_NUM_ENTRIES
};

static int g_state;
static char *g_state_names[STATE_NUM_ENTRIES] = {"Init", "Run", "Single step", "Precedure step"};


typedef struct _sbp_t
{
	uint32_t *pAddr;
	uint32_t instr;
} bp_t;

static EXCEPTION_CONTEXT xcp_last;
static bp_t user_bp[MAX_USER_BP];
static bp_t mgmt_bp_ss[2];
static bp_t mgmt_bp_ru[2];
static int g_is_ss;
static int g_bp_count;

#if 1
extern void dbg_putchar(char c);
extern char dbg_getchar();

void dbg_puts(const char *buffer)
{
	while(*buffer)
	{
		dbg_putchar(*buffer);
		buffer++;
	}
}

void dbg_print_byte(char byte)
{
	int i;
	unsigned char c, nibble;

	for (i=0; i < 2; i++)
	{
		nibble = (char)((byte >> 4) & 0xF);
		byte <<= 4;

		if (nibble < 10)
			c = nibble + '0';
		else
			c = nibble + 'A' - 10;

		dbg_putchar(c);
	}
}

void dbg_print_word(int word)
{
	int i;
	unsigned char c;

	for (i=0; i < 4; i++)
	{
		c = (char) (word >> 24);
		dbg_print_byte(c);
		word <<= 8;
	}
}

int dbg_gets(char *buffer, size_t size)
{
	size_t len = 0;
	while(size)
	{
		char c = dbg_getchar();
		if (c == 0x0A || c == 0x0D)
		{
			if (len)
			{
				break;
			}
		}
		else
		{
			buffer[len++] = c;
			dbg_putchar(c);
			if (len == size)
			{
				break;
			}
		}
	}
	buffer[len] = 0;
	dbg_putchar(0x0D);
	dbg_putchar(0x0A);
	return len;
}
#endif

int IsBreak(uint32_t instr)
{
	return ((instr & 0xFC00003F) == 0x0000000D);
}

uint32_t BreakGetType(uint32_t instr)
{
	return (instr >> 6) & BP_MASK_TYPE;
}

char* reg_changed(uint32_t reg1, uint32_t reg2)
{
	static char chg_str[2] = {0};

	if (reg1 != reg2)
		chg_str[0] = '*';
	else
		chg_str[0] = ' ';

	return chg_str;
}

void set_mgmt_break(uint32_t *pAddr_break)
{
	mgmt_bp_ss[0].pAddr = NULL;
	mgmt_bp_ss[0].pAddr = 0;

	// Don't overwrite user breaks
	if (IsBreak(*pAddr_break) && (BreakGetType(*pAddr_break) == BP_USER_BASE))
	{
//		dbg_puts("Instruction at address ");dbg_print_word((long)pAddr_break);dbg_puts(" is user break\n");
	}
	else
	{
		// Save original instruction
		mgmt_bp_ss[0].pAddr = pAddr_break;
		mgmt_bp_ss[0].instr = *(mgmt_bp_ss[0].pAddr);
		// Replace instruction with managment breakpoint
		*(mgmt_bp_ss[0].pAddr) = BP_MGMT_SS(1);
		ICACHE_invalidate_at(mgmt_bp_ss[0].pAddr);
	}
}

void singlestep(struct xcptcontext * xcp, uint32_t *pAddr_curr, uint32_t is_branch_shadow)
{

    int junk;
 	uint32_t branch_addr, reg, result, bp_type;
	uint32_t *pInstr, *pAddr_prev, *pAddr_next;

	pAddr_prev = pAddr_curr - 1;
	pAddr_next = pAddr_curr + 1;

	set_mgmt_break(pAddr_next);

	mgmt_bp_ss[1].pAddr = NULL;
	mgmt_bp_ss[1].pAddr = 0;

	// We have two possible management breaks, if previous instruction was branch or jump
	if (is_branch_shadow)
	{
		result = tdisasm(g_buf, (long)pAddr_prev, *pAddr_prev, 0, &junk, &branch_addr, &reg);
		// Is jump target stored in register
		if (result == 3)
		{
			branch_addr = xcp->regs[reg&0x1F];
		}

	// Don't overwrite user breaks
		if (IsBreak(branch_addr) && (BreakGetType(branch_addr) == BP_USER_BASE))
		{
//			dbg_puts("Instruction at branch address ");dbg_print_word((long)branch_addr);dbg_puts(" is user break\n");
		}
		else
		{
			// Save original instruction
			mgmt_bp_ss[1].pAddr = (uint32_t*)branch_addr;
			mgmt_bp_ss[1].instr = *(mgmt_bp_ss[1].pAddr);
			// Replace instruction with managment breakpoint
			*(mgmt_bp_ss[1].pAddr) = BP_MGMT_SS(2);
			ICACHE_invalidate_at(mgmt_bp_ss[1].pAddr);
		}
	}
}

void dbg_handler(struct xcptcontext * xcp)
{

 	uint32_t bp_addr, bp_index = 0, branch_addr, reg, result, bp_type;
    int junk, i, leave_isr, is_branch_shadow, is_user_bp;
	uint32_t *pInstr, *pAddr_curr, *pAddr_prev, *pAddr_next;
	instr_info_t info;

	is_user_bp = 0;
	pAddr_curr = (uint32_t*)xcp->epc;
	is_branch_shadow = ((xcp->cr & 0x80000000) == 0x80000000);
	if (is_branch_shadow)
		pAddr_curr++;

	pAddr_prev = pAddr_curr - 1;
	pAddr_next = pAddr_curr + 1;

	if (IsBreak(*pAddr_curr))
	{
		bp_type = BreakGetType(*pAddr_curr);

		switch (bp_type)
		{
			case BP_MGMT_BASE_SS:

			// Restore original instructions after single-step
//			dbg_puts("1. Restore after single-step at ");dbg_print_word((long)mgmt_bp_ss[0].pAddr);dbg_puts("\n\r");
			*(mgmt_bp_ss[0].pAddr) = mgmt_bp_ss[0].instr;
			ICACHE_invalidate_at(mgmt_bp_ss[0].pAddr);
			if (mgmt_bp_ss[1].pAddr)
			{
//				dbg_puts("2. Restore after single-step at ");dbg_print_word((long)mgmt_bp_ss[1].pAddr);dbg_puts("\n\r");
				*(mgmt_bp_ss[1].pAddr) = mgmt_bp_ss[1].instr;
				ICACHE_invalidate_at(mgmt_bp_ss[1].pAddr);
			}

			break;

			case BP_MGMT_BASE_RU:

			bp_index = BP_GET_ID(*pAddr_curr);
//			dbg_puts("Restore user break at ");dbg_print_word((long)user_bp[bp_index].pAddr);dbg_puts("\n\r");

			*(user_bp[bp_index].pAddr) = BP_USER(bp_index);
			ICACHE_invalidate_at(user_bp[bp_index].pAddr);

			*(mgmt_bp_ru[0].pAddr) = mgmt_bp_ru[0].instr;
			ICACHE_invalidate_at(mgmt_bp_ru[0].pAddr);
//			dbg_puts("1. Restore after RU at ");dbg_print_word((long)mgmt_bp_ru[0].pAddr);dbg_puts("\n\r");
			if (mgmt_bp_ru[1].pAddr)
			{
				*(mgmt_bp_ru[1].pAddr) = mgmt_bp_ru[1].instr;
				ICACHE_invalidate_at(mgmt_bp_ru[1].pAddr);
//				dbg_puts("2. Restore after RU at ");dbg_print_word((long)mgmt_bp_ru[1].pAddr);dbg_puts("\n\r");
			}
			if (!g_is_ss)
				return;

			break;

			case BP_USER_BASE:

			is_user_bp = 1;
			bp_index = BP_GET_ID(*pAddr_curr);
//			dbg_puts("Restore instruction at ");dbg_print_word((long)user_bp[bp_index].pAddr);dbg_puts("\n\r");
			*(user_bp[bp_index].pAddr) = user_bp[bp_index].instr;
			ICACHE_invalidate_at(user_bp[bp_index].pAddr);
			break;

			default:
//			dbg_puts("Found ordinary break at ");dbg_print_word((long)pAddr_curr);dbg_puts("\n\r");
			break;

		}
	}

	dbg_puts("\n\r");
	DBG_PRINT_REG_CHG(" Status : ", xcp->sr, reg_changed(xcp->sr, xcp_last.sr));
	DBG_PRINT_REG_CHG("  Cause : ", xcp->cr, reg_changed(xcp->cr, xcp_last.cr));
	DBG_PRINT_REG_CHG("    EPC : ", xcp->epc, reg_changed(xcp->epc, xcp_last.epc));
	DBG_PRINT_REG_CHG("BadAddr : ", xcp->baddr, reg_changed(xcp->baddr, xcp_last.baddr));
	dbg_puts("\n\r");
	DBG_PRINT_REG_CHG("   MDLO : ", xcp->mdlo, reg_changed(xcp->mdlo, xcp_last.mdlo));
	DBG_PRINT_REG_CHG("   MDHI : ", xcp->mdhi, reg_changed(xcp->mdhi, xcp_last.mdhi));

	dbg_puts("\n\r");

	dbg_puts("Registers:\n\r");
	DBG_PRINT_REG_CHG(" 0 (ze) : ", xcp->regs[0], reg_changed(xcp->regs[0], xcp_last.regs[0]));
	DBG_PRINT_REG_CHG(" 1 (at) : ", xcp->regs[1], reg_changed(xcp->regs[1], xcp_last.regs[1]));
	DBG_PRINT_REG_CHG(" 2 (v0) : ", xcp->regs[2], reg_changed(xcp->regs[2], xcp_last.regs[2]));
	DBG_PRINT_REG_CHG(" 3 (v1) : ", xcp->regs[3], reg_changed(xcp->regs[3], xcp_last.regs[3]));
	dbg_puts("\n\r");
	DBG_PRINT_REG_CHG(" 4 (a0) : ", xcp->regs[4], reg_changed(xcp->regs[4], xcp_last.regs[4]));
	DBG_PRINT_REG_CHG(" 5 (a1) : ", xcp->regs[5], reg_changed(xcp->regs[5], xcp_last.regs[5]));
	DBG_PRINT_REG_CHG(" 6 (a2) : ", xcp->regs[6], reg_changed(xcp->regs[6], xcp_last.regs[6]));
	DBG_PRINT_REG_CHG(" 7 (a3) : ", xcp->regs[7], reg_changed(xcp->regs[7], xcp_last.regs[7]));
	dbg_puts("\n\r");
	DBG_PRINT_REG_CHG(" 8 (t0) : ", xcp->regs[8], reg_changed(xcp->regs[8], xcp_last.regs[8]));
	DBG_PRINT_REG_CHG(" 9 (t1) : ", xcp->regs[9], reg_changed(xcp->regs[9], xcp_last.regs[9]));
	DBG_PRINT_REG_CHG("10 (t2) : ", xcp->regs[10], reg_changed(xcp->regs[10], xcp_last.regs[10]));
	DBG_PRINT_REG_CHG("11 (t3) : ", xcp->regs[11], reg_changed(xcp->regs[11], xcp_last.regs[11]));
	dbg_puts("\n\r");
	DBG_PRINT_REG_CHG("12 (t4) : ", xcp->regs[12], reg_changed(xcp->regs[12], xcp_last.regs[12]));
	DBG_PRINT_REG_CHG("13 (t5) : ", xcp->regs[13], reg_changed(xcp->regs[13], xcp_last.regs[13]));
	DBG_PRINT_REG_CHG("14 (t6) : ", xcp->regs[14], reg_changed(xcp->regs[14], xcp_last.regs[14]));
	DBG_PRINT_REG_CHG("15 (t7) : ", xcp->regs[15], reg_changed(xcp->regs[15], xcp_last.regs[15]));
	dbg_puts("\n\r");
	DBG_PRINT_REG_CHG("16 (s0) : ", xcp->regs[16], reg_changed(xcp->regs[16], xcp_last.regs[16]));
	DBG_PRINT_REG_CHG("17 (s1) : ", xcp->regs[17], reg_changed(xcp->regs[17], xcp_last.regs[17]));
	DBG_PRINT_REG_CHG("18 (s2) : ", xcp->regs[18], reg_changed(xcp->regs[18], xcp_last.regs[18]));
	DBG_PRINT_REG_CHG("19 (s3) : ", xcp->regs[19], reg_changed(xcp->regs[19], xcp_last.regs[19]));
	dbg_puts("\n\r");
	DBG_PRINT_REG_CHG("20 (s4) : ", xcp->regs[20], reg_changed(xcp->regs[20], xcp_last.regs[20]));
	DBG_PRINT_REG_CHG("21 (s5) : ", xcp->regs[21], reg_changed(xcp->regs[21], xcp_last.regs[21]));
	DBG_PRINT_REG_CHG("22 (s6) : ", xcp->regs[22], reg_changed(xcp->regs[22], xcp_last.regs[22]));
	DBG_PRINT_REG_CHG("23 (s7) : ", xcp->regs[23], reg_changed(xcp->regs[23], xcp_last.regs[23]));
	dbg_puts("\n\r");
	DBG_PRINT_REG_CHG("24 (s8) : ", xcp->regs[24], reg_changed(xcp->regs[24], xcp_last.regs[24]));
	DBG_PRINT_REG_CHG("25 (s9) : ", xcp->regs[25], reg_changed(xcp->regs[25], xcp_last.regs[25]));
	DBG_PRINT_REG_CHG("26 (k0) : ", xcp->regs[26], reg_changed(xcp->regs[26], xcp_last.regs[26]));
	DBG_PRINT_REG_CHG("27 (k1) : ", xcp->regs[27], reg_changed(xcp->regs[27], xcp_last.regs[27]));
	dbg_puts("\n\r");
	DBG_PRINT_REG_CHG("28 (gp) : ", xcp->regs[28], reg_changed(xcp->regs[28], xcp_last.regs[28]));
	DBG_PRINT_REG_CHG("29 (sp) : ", xcp->regs[29], reg_changed(xcp->regs[29], xcp_last.regs[29]));
	DBG_PRINT_REG_CHG("30 (fp) : ", xcp->regs[30], reg_changed(xcp->regs[30], xcp_last.regs[30]));
	DBG_PRINT_REG_CHG("31 (ra) : ", xcp->regs[31], reg_changed(xcp->regs[31], xcp_last.regs[31]));
	dbg_puts("\n\r");
	dbg_puts("\n\r");

//	dbg_puts(g_state_names[g_state]);dbg_puts("\n\r");
//	dbg_puts("\n\r");

	pInstr = pAddr_prev;
	// Disassemble instructions
    for (i=0; i < 3; i++)
    {
		dbg_print_word((long)pInstr);
		if (pInstr != pAddr_curr)
		{
			if (IsBreak(*pInstr) && (BreakGetType(*pInstr) == BP_USER_BASE))
			{
				tdisasm(g_buf, (long)user_bp[BP_GET_ID(*pInstr)].pAddr, user_bp[BP_GET_ID(*pInstr)].instr, 0, &junk, &junk, &junk);
				dbg_puts(": b("); dbg_print_byte((char)BP_GET_ID(*pInstr)); dbg_puts(")   ");
			}
			else
			{
				tdisasm(g_buf, (long)pInstr, *pInstr, 0, &junk, &junk, &junk);
				dbg_puts(":         ");
			}
		}
		else
		{
			tdisasm(g_buf, (long)pInstr, *pInstr, 0, &junk, &junk, &junk);
			if (is_user_bp)
			{
				dbg_puts(": b("); dbg_print_byte((char)bp_index); dbg_puts(")-> ");
			}
			else
			{
				dbg_puts(":      -> ");
			}
		}
		dbg_puts(g_buf);
		dbg_puts("\n\r");
		pInstr++;
	}

	if (is_user_bp)
	{
		// Save original instruction
		mgmt_bp_ru[0].pAddr = pAddr_next;
		mgmt_bp_ru[0].instr = *(mgmt_bp_ru[0].pAddr);
		// Replace instruction with managment breakpoint
		*(mgmt_bp_ru[0].pAddr) = BP_MGMT_RU(bp_index);
		ICACHE_invalidate_at(mgmt_bp_ru[0].pAddr);
		mgmt_bp_ru[1].pAddr = NULL;
		mgmt_bp_ru[1].pAddr = 0;
//		dbg_puts("1. Insert RU-break at ");dbg_print_word((long)mgmt_bp_ru[0].pAddr);dbg_puts("\n\r");

		// We have two possible management breaks, if previous instruction was branch or jump
		if (is_branch_shadow)
		{
			result = tdisasm(g_buf, (long)pAddr_prev, *pAddr_prev, 0, &junk, &branch_addr, &reg);
			// Is jump target stored in register
			if (result == 3)
			{
				branch_addr = xcp->regs[reg&0x1F];
			}
			// Save original instruction
			mgmt_bp_ru[1].pAddr = (uint32_t*)branch_addr;
			mgmt_bp_ru[1].instr = *(mgmt_bp_ru[1].pAddr);
			// Replace instruction with managment breakpoint
			*(mgmt_bp_ru[1].pAddr) = BP_MGMT_RU(bp_index);
			ICACHE_invalidate_at(mgmt_bp_ru[1].pAddr);
//			dbg_puts("2. Insert RU-break at ");dbg_print_word((long)mgmt_bp_ru[1].pAddr);dbg_puts("\n\r");
		}
	}

	do
	{
		char buffer[33];
		leave_isr = 0;
		switch(dbg_getchar())
		{
			case 'g':
			g_state = STATE_RUN;
			leave_isr = 1;
			g_is_ss = 0;
			if (IsBreak(*pAddr_curr))
			{
				if (BreakGetType(*pAddr_curr) != BP_USER_BASE)
				{
					xcp->epc += 4;		// Skip ordinary program breaks
				}
			}
			break;

			case 'b':
			dbg_puts("Enter breakpoint: ");
			dbg_gets(buffer, sizeof(buffer));
			bp_addr = strtol(buffer, NULL, 16);
			dbg_puts("Insert breakpoint at "); dbg_print_word(bp_addr); dbg_puts("\n\r");

			user_bp[g_bp_count].pAddr = (uint32_t*)bp_addr;
			user_bp[g_bp_count].instr = *(user_bp[g_bp_count].pAddr);
			*(user_bp[g_bp_count].pAddr) = BP_USER(g_bp_count);

		    tdisasm(g_buf, (long)user_bp[g_bp_count].pAddr, user_bp[g_bp_count].instr, 0, &junk, &junk, &junk);
			dbg_print_word((long)user_bp[g_bp_count].pAddr);dbg_puts(": b   ");dbg_puts(g_buf);dbg_puts("\n\r");
			ICACHE_invalidate_at(user_bp[g_bp_count].pAddr);
			g_bp_count++;
			break;

			case 's':
			g_state = STATE_STEP_SINGLE;
			g_is_ss = 1;
			leave_isr = 1;

			if (is_user_bp)
				break;

			if (IsBreak(*pAddr_curr))
			{
				if (BreakGetType(*pAddr_curr) == BP_USER_BASE)
				{
					break;
				}
				else
				{
					xcp->epc += 4;		// Skip ordinary program breaks
				}
			}

			singlestep(xcp, pAddr_curr, is_branch_shadow);
			break;

			case 'e':
			g_state = STATE_STEP_SINGLE;
			g_is_ss = 1;
			leave_isr = 1;

			if (is_user_bp)
				break;

			if (IsBreak(*pAddr_curr))
			{
				if (BreakGetType(*pAddr_curr) == BP_USER_BASE)
				{
					break;
				}
				else
				{
					xcp->epc += 4;		// Skip ordinary program breaks
				}
			}

			pInstr = pAddr_curr;

			do
			{
				result = instr_info(*pInstr, &info);
				if (result == INSTR_TYPE_JUMP)
				{
					if (info.rs == 0x1F)
						break;
				}
				else if (result == INSTR_TYPE_LOAD)
				{
					if (info.rs == 0x1F)
						break;
				}
				pInstr++;
			} while(1);

//			dbg_puts("Return found at "); dbg_print_word((long)pInstr);dbg_puts("\n\r");
			set_mgmt_break(pInstr);
			break;

			case 'p':
			g_state = STATE_STEP_PROC;
			g_is_ss = 1;
			leave_isr = 1;

			if (is_user_bp)
				break;

			if (IsBreak(*pAddr_curr))
			{
				if (BreakGetType(*pAddr_curr) == BP_USER_BASE)
				{
					break;
				}
				else
				{
					xcp->epc += 4;		// Skip ordinary program breaks
				}
			}

			result = instr_info(*pAddr_curr, &info);
			if ((result == INSTR_TYPE_JUMP) && (info.flags & INSTR_FLAGS_JUMP_LINK))
			{
				singlestep(xcp, pAddr_next, 0);
//				printf("Skip sub-routine\n");
			}
			else
			{
				singlestep(xcp, pAddr_curr, is_branch_shadow);
			}
			break;

			default:
			break;
		}
	} while (!leave_isr);

	memcpy(&xcp_last, xcp, sizeof(EXCEPTION_CONTEXT));
}

void debug_int(struct xcptcontext * xcp)
{
	dbg_handler(xcp);

}

int debug_break(struct xcptcontext * xcp)
{
	dbg_handler(xcp);
	return 0;

}

void dbg_init(void)
{
	memset(&xcp_last, 0, sizeof(EXCEPTION_CONTEXT));
	g_state = STATE_INIT;
	xcpt_register(EXC_BP, debug_break);
}