//##########+++ Decode Format III Instructions +++##########
//# Format III are double operand of the form:
//# [CCCC][SSSS][ABaa][DDDD]
//#
//# Where C = Opcode, B = Byte/Word flag,
//# A = Addressing mode for destination
//# a = Addressing mode for source
//# S = Source, D = Destination
//########################################################
void decode_formatIII( unsigned short instruction ){
unsigned char opcode = ( instruction & 0xF000 ) >> 12;
unsigned char source = ( instruction & 0x0F00 ) >> 8;
unsigned char as_flag = (instruction & 0x0030 ) >> 4;
unsigned char destination = ( instruction & 0x000F );
unsigned char ad_flag = (instruction & 0x0080 ) >> 7;
unsigned char bw_flag = (instruction & 0x0040 ) >> 6;
char source_reg[10], dest_reg[10];
printf("Source: %04X\nas_flag: %02X\nDest: %04X\nad_flag: %X\nbw_flag: %X\n",
source, as_flag, destination, ad_flag, bw_flag);
switch( opcode ){
//# MOV source to destination
case 0x4:{
bw_flag == 0 ? printf("MOV ") : printf("MOV.B ");
//# Both operands are register contents
if( as_flag == 0 && ad_flag == 0 ){
reg_num_to_name(source, source_reg);
reg_num_to_name(destination, dest_reg);
printf("%s, %s\n", source_reg, dest_reg);
short *source_reg = get_reg_ptr(source);
short *dest_reg = get_reg_ptr(destination);
*dest_reg = *source_reg;
break;
}
//# Indexed mode X(Rn) (Rn+X) points to the operand
//# X is stored in the next word
else if( as_flag == 1 && ad_flag == 1 ){
unsigned short source_offset, dest_offset;
reg_num_to_name(source, source_reg);
reg_num_to_name(destination, dest_reg);
source_offset = fetch();
dest_offset = fetch();
printf("0x%04X(%s), 0x%04X(%s)\n", source_offset, source_reg, dest_offset, dest_reg);
break;
}
//# Indexed mode for only source operand
else if( as_flag == 1 && ad_flag == 0 ){
unsigned short source_offset, source_contents;
unsigned short* source_ptr;
short* dest_ptr;
reg_num_to_name(source, source_reg);
reg_num_to_name(destination, dest_reg);
source_offset = fetch();
printf("0x%04X(%s), %s\n", source_offset, source_reg, dest_reg);
source_ptr = get_reg_ptr(source);
dest_ptr = get_reg_ptr(destination);
source_contents = *source_ptr;
printf("Got contents 0x%04X\n", source_contents + source_offset);
void* addr = (void*)MEMSPACE;
addr += (source_contents + source_offset);
*dest_ptr = *( (short*)addr );
break;
}
//# Indexed mode for only destination operand
else if( as_flag == 0 && ad_flag == 1 ){
unsigned short dest_offset;
reg_num_to_name(source, source_reg);
reg_num_to_name(destination, dest_reg);
dest_offset = fetch();
printf("%s, 0x%04X(%s)\n", source_reg, dest_offset, dest_reg);
break;
}
//# Constant mode for only source operand
else if( as_flag == 3 && ad_flag == 0 ){
short source_const;
reg_num_to_name(destination, dest_reg);
source_const = fetch();
printf("0x%04X, %s\n", source_const, dest_reg);
break;
}
//# SRC = Constant, DST = Address
else if( as_flag == 3 && ad_flag == 1 ){
short source_const;
unsigned short dest_addr;
source_const = fetch();
dest_addr = fetch();
printf("#0x%04X, &0x%04X\n", source_const, dest_addr);
}
//# Indirect register mode for only source operand
else if( as_flag == 2 && ad_flag == 0 ){
short source_const;
reg_num_to_name(destination, dest_reg);
reg_num_to_name(source, source_reg);
printf("@%s, %s\n", source_reg, dest_reg);
break;
}
break;
}
//# ADD source to destination
case 0x5:{
printf("ADD\n");
break;
}
//# ADDC Add w/ carry dst += (src+C)
case 0x6:{
printf("ADDC\n");
break;
}
//# SUBC Sub w/carry dst -= (src+C)
case 0x7:{
printf("SUBC\n");
break;
}
//# SUB dst -= src
case 0x8:{
printf("SUB\n");
break;
}
//# CMP compare (dst-src) discard result
case 0x9:{
printf("CMP\n");
break;
}
//# DADD Decimal addition dst += src
case 0xA:{
printf("DADD\n");
break;
}
//# BIT Test bits dst & src, discard result
case 0xB:{
printf("BIT\n");
break;
}
//# BIC, bit clear dest &= ~src
case 0xC:{
printf("BIC\n");
break;
}
//# BIS Bit set - logical OR dest |= src
case 0xD:{
printf("BIS\n");
break;
}
//# XOR, bitwise XOR; dst ^= src
case 0xE:{
printf("XOR\n");
break;
}
//# AND, bitwise AND; dst &= src
case 0xF:{
printf("AND\n");
break;
}
} //# End of switch
}
void decode_formatI(Emulator *emu, uint16_t instruction, bool disassemble)
{
Cpu *cpu = emu->cpu;
Debugger *debugger = emu->debugger;
uint8_t opcode = (instruction & 0xF000) >> 12;
uint8_t source = (instruction & 0x0F00) >> 8;
uint8_t as_flag = (instruction & 0x0030) >> 4;
uint8_t destination = (instruction & 0x000F);
uint8_t ad_flag = (instruction & 0x0080) >> 7;
uint8_t bw_flag = (instruction & 0x0040) >> 6;
char s_reg_name[10], d_reg_name[10];
char mnemonic[100] = {0};
/* String to show hex value of instruction */
char hex_str[100] = {0};
char hex_str_part[10] = {0};
sprintf(hex_str, "%04X", instruction);
/* Source Register pointer */
int16_t *s_reg = get_reg_ptr(emu, source);
/* Destination Register pointer */
int16_t *d_reg = get_reg_ptr(emu, destination);
reg_num_to_name(source, s_reg_name); /* Get source register name */
reg_num_to_name(destination, d_reg_name); /* Get destination register name */
uint8_t constant_generator_active = 0; /* Specifies if CG1/CG2 active */
int16_t immediate_constant = 0; /* Generated Constant */
/* Spot CG1 and CG2 Constant generator instructions */
if ( (source == 2 && as_flag > 1) || source == 3 ) {
constant_generator_active = 1;
immediate_constant = run_constant_generator(source, as_flag);
}
else {
constant_generator_active = 0;
}
/* Identify the nature of instruction operand addressing modes */
int16_t source_value, source_offset;
int16_t destination_offset;
uint16_t *destination_addr;
char asm_operands[20] = {0}, asm_op2[20] = {0};
/* Register - Register; Ex: MOV Rs, Rd */
/* Constant Gen - Register; Ex: MOV #C, Rd */ /* 0 */
if (as_flag == 0 && ad_flag == 0) {
if (constant_generator_active) { /* Source Constant */
source_value = immediate_constant;
sprintf(asm_operands, "#0x%04X, %s",
(uint16_t) source_value, d_reg_name);
}
else { /* Source register */
source_value = *s_reg;
sprintf(asm_operands, "%s, %s", s_reg_name, d_reg_name);
}
destination_addr = d_reg; /* Destination Register */
if (!disassemble) {
bw_flag == BYTE ? *d_reg &= 0x00FF : 0;
}
}
/* Register - Indexed; Ex: MOV Rs, 0x0(Rd) */
/* Register - Symbolic; Ex: MOV Rs, 0xD */
/* Register - Absolute; Ex: MOV Rs, &0xD */
/* Constant Gen - Indexed; Ex: MOV #C, 0x0(Rd) */ /* 0 */
/* Constant Gen - Symbolic; Ex: MOV #C, 0xD */ /* 0 */
/* Constant Gen - Absolute; Ex: MOV #C, &0xD */ /* 0 */
else if (as_flag == 0 && ad_flag == 1) {
destination_offset = fetch(emu);
sprintf(hex_str_part, "%04X", (uint16_t) destination_offset);
strncat(hex_str, hex_str_part, sizeof hex_str);
destination_addr = get_addr_ptr(*d_reg + destination_offset);
if (constant_generator_active) { /* Source Constant */
source_value = immediate_constant;
sprintf(asm_operands, "#0x%04X, ", source_value);
}
else { /* Source from register */
source_value = *s_reg;
sprintf(asm_operands, "%s, ", s_reg_name);
}
if (destination == 0) { /* Destination Symbolic */
uint16_t virtual_addr = *d_reg + destination_offset - 2;
destination_addr = get_addr_ptr(virtual_addr);
sprintf(asm_op2, "0x%04X", (uint16_t) virtual_addr);
}
else if (destination == 2) { /* Destination Absolute */
destination_addr = get_addr_ptr(destination_offset);
sprintf(asm_op2, "&0x%04X", (uint16_t) destination_offset);
}
else { /* Destination Indexed */
sprintf(asm_op2, "0x%04X(%s)",
(uint16_t) destination_offset, d_reg_name);
}
strncat(asm_operands, asm_op2, sizeof asm_op2);
}
/* Indexed - Register; Ex: MOV 0x0(Rs), Rd */
/* Symbolic - Register; Ex: MOV 0xS, Rd */
/* Absolute - Register; Ex: MOV &0xS, Rd */
/* Constant Gen - Register; Ex: MOV #C, Rd */ /* 1 */
else if (as_flag == 1 && ad_flag == 0) {
if (constant_generator_active) { /* Source Constant */
source_value = immediate_constant;
sprintf(asm_operands, "#0x%04X, %s", source_value, d_reg_name);
}
else if (source == 0) { /* Source Symbolic */
source_offset = fetch(emu);
uint16_t virtual_addr = *s_reg + source_offset - 2;
source_value = *get_addr_ptr(virtual_addr);
sprintf(hex_str_part, "%04X", (uint16_t) source_offset);
strncat(hex_str, hex_str_part, sizeof hex_str);
sprintf(asm_operands, "0x%04X, %s", virtual_addr, d_reg_name);
}
else if (source == 2) { /* Source Absolute */
source_offset = fetch(emu);
source_value = *get_addr_ptr(source_offset);
sprintf(hex_str_part, "%04X", (uint16_t) source_offset);
strncat(hex_str, hex_str_part, sizeof hex_str);
sprintf(asm_operands, "&0x%04X, %s",
(uint16_t) source_offset, d_reg_name);
}
else { /* Source Indexed */
source_offset = fetch(emu);
source_value = *get_addr_ptr(*s_reg + source_offset);
sprintf(hex_str_part, "%04X", (uint16_t) source_offset);
strncat(hex_str, hex_str_part, sizeof hex_str);
sprintf(asm_operands, "0x%04X(%s), %s",
(uint16_t) source_offset, s_reg_name, d_reg_name);
}
destination_addr = d_reg; /* Destination register */
if (!disassemble) {
bw_flag == BYTE ? *d_reg &= 0x00FF : 0;
}
}
/* Indexed - Indexed; Ex: MOV 0x0(Rs), 0x0(Rd) */
/* Symbolic - Indexed; Ex: MOV 0xS, 0x0(Rd) */
/* Indexed - Symbolic; Ex: MOV 0x0(Rd), 0xD */
/* Symbolic - Symbolic; Ex: MOV 0xS, 0xD */
/* Absolute - Indexed; Ex: MOV &0xS, 0x0(Rd) */
/* Indexed - Absolute; Ex: MOV 0x0(Rs), &0xD */
/* Absolute - Absolute; Ex: MOV &0xS, &0xD */
/* Absolute - Symbolic; Ex: MOV &0xS, 0xD */
/* Symbolic - Absolute; Ex: MOV 0xS, &0xD */
/* Constant Gen - Indexed; Ex: MOV #C, 0x0(Rd) */ /* 1 */
/* Constant Gen - Symbolic; Ex: MOV #C, 0xD */ /* 1 */
/* Constant Gen - Absolute; Ex: MOV #C, &0xD */ /* 1 */
else if (as_flag == 1 && ad_flag == 1) {
if (constant_generator_active) { /* Source Constant */
source_value = immediate_constant;
sprintf(asm_operands, "#0x%04X, ", source_value);
}
else if (source == 0) { /* Source Symbolic */
source_offset = fetch(emu);
uint16_t virtual_addr = cpu->pc + source_offset - 4;
source_value = *get_addr_ptr(virtual_addr);
sprintf(hex_str_part, "%04X", (uint16_t) source_offset);
strncat(hex_str, hex_str_part, sizeof hex_str);
sprintf(asm_operands, "0x%04X, ", virtual_addr);
}
else if (source == 2) { /* Source Absolute */
source_offset = fetch(emu);
source_value = *get_addr_ptr(source_offset);
sprintf(hex_str_part, "%04X", (uint16_t) source_offset);
strncat(hex_str, hex_str_part, sizeof hex_str);
sprintf(asm_operands, "&0x%04X, ", (uint16_t) source_offset);
}
else { /* Source Indexed */
source_offset = fetch(emu);
source_value = *get_addr_ptr(*s_reg + source_offset);
sprintf(hex_str_part, "%04X", (uint16_t)source_offset);
strncat(hex_str, hex_str_part, sizeof hex_str);
sprintf(asm_operands, "0x%04X(%s), ",
(uint16_t) source_offset, s_reg_name);
}
destination_offset = fetch(emu);
sprintf(hex_str_part, "%04X", (uint16_t) destination_offset);
strncat(hex_str, hex_str_part, sizeof hex_str);
if (destination == 0) { /* Destination Symbolic */
uint16_t virtual_addr = cpu->pc + destination_offset - 2;
destination_addr = get_addr_ptr(virtual_addr);
sprintf(asm_op2, "0x%04X", virtual_addr);
}
else if (destination == 2) { /* Destination Absolute */
destination_addr = get_addr_ptr(destination_offset);
sprintf(asm_op2, "&0x%04X", (uint16_t) destination_offset);
}
else { /* Destination indexed */
destination_addr = get_addr_ptr(*d_reg + destination_offset);
sprintf(asm_op2, "0x%04X(%s)", (uint16_t)destination_offset, d_reg_name);
}
strncat(asm_operands, asm_op2, sizeof asm_op2);
}
/* Indirect - Register; Ex: MOV @Rs, Rd */
/* Constant Gen - Register; Ex: MOV #C, Rd */ /* 2, 4 */
else if (as_flag == 2 && ad_flag == 0) {
if (constant_generator_active) { /* Source Constant */
source_value = immediate_constant;
sprintf(asm_operands, "#0x%04X, %s", immediate_constant, d_reg_name);
}
else { /* Source Indirect */
source_value = *get_addr_ptr(*s_reg);
sprintf(asm_operands, "@%s, %s", s_reg_name, d_reg_name);
}
destination_addr = d_reg; /* Destination Register */
if (!disassemble) {
bw_flag == BYTE ? *d_reg &= 0x00FF : 0;
}
}
/* Indirect - Indexed; Ex: MOV @Rs, 0x0(Rd) */
/* Indirect - Symbolic; Ex: MOV @Rs, 0xD */
/* Indirect - Absolute; Ex: MOV @Rs, &0xD */
/* Constant Gen - Indexed; Ex: MOV #C, 0x0(Rd) */ /* 2, 4 */
/* Constant Gen - Symbolic; Ex: MOV #C, 0xD */ /* 2, 4 */
/* Constant Gen - Absolute; Ex: MOV #C, &0xD */ /* 2, 4 */
else if (as_flag == 2 && ad_flag == 1) {
destination_offset = fetch(emu);
sprintf(hex_str_part, "%04X", (uint16_t) destination_offset);
strncat(hex_str, hex_str_part, sizeof hex_str);
if (constant_generator_active) { /* Source Constant */
source_value = immediate_constant;
sprintf(asm_operands, "#0x%04X, ", source_value);
}
else { /* Source Indirect */
source_value = *get_addr_ptr(*s_reg);
sprintf(asm_operands, "@%s, ", s_reg_name);
}
if (destination == 0) { /* Destination Symbolic */
uint16_t virtual_addr = cpu->pc + destination_offset - 2;
destination_addr = get_addr_ptr(virtual_addr);
sprintf(asm_op2, "0x%04X", virtual_addr);
}
else if (destination == 2) { /* Destination Absolute */
destination_addr = get_addr_ptr(destination_offset);
sprintf(asm_op2, "&0x%04X", destination_offset);
}
else { /* Destination Indexed */
destination_addr = get_addr_ptr(*d_reg + destination_offset);
sprintf(asm_op2, "0x%04X(%s)", (uint16_t)destination_offset, d_reg_name);
}
strncat(asm_operands, asm_op2, sizeof asm_op2);
}
/* Indirect Inc - Register; Ex: MOV @Rs+, Rd */
/* Immediate - Register; Ex: MOV #S, Rd */
/* Constant Gen - Register; Ex: MOV #C, Rd */ /* -1, 8 */
else if (as_flag == 3 && ad_flag == 0) {
if (constant_generator_active) { /* Source Constant */
source_value = immediate_constant;
sprintf(asm_operands, "#0x%04X, %s",
(uint16_t) source_value, d_reg_name);
}
else if (source == 0) { /* Source Immediate */
source_value = fetch(emu);
sprintf(hex_str_part, "%04X", (uint16_t) source_value);
strncat(hex_str, hex_str_part, sizeof hex_str);
if (bw_flag == WORD) {
sprintf(asm_operands, "#0x%04X, %s",
(uint16_t) source_value, d_reg_name);
}
else if (bw_flag == BYTE) {
sprintf(asm_operands, "#0x%04X, %s",
(uint8_t) source_value, d_reg_name);
}
}
else { /* Source Indirect AutoIncrement */
source_value = *get_addr_ptr(*s_reg);
sprintf(asm_operands, "@%s+, %s", s_reg_name, d_reg_name);
if (!disassemble) {
bw_flag == WORD ? *s_reg += 2 : (*s_reg += 1);
}
}
destination_addr = d_reg; /* Destination Register */
if (!disassemble) {
bw_flag == BYTE ? *d_reg &= 0x00FF : 0;
}
}
/* Indirect Inc - Indexed; Ex: MOV @Rs+, 0x0(Rd) */
/* Indirect Inc - Symbolic; Ex: MOV @Rs+, 0xD */
/* Indirect Inc - Absolute; Ex: MOV @Rs+, &0xD */
/* Immediate - Indexed; Ex: MOV #S, 0x0(Rd) */
/* Immediate - Symbolic; Ex: MOV #S, 0xD */
/* Immediate - Absolute; Ex: MOV #S, &0xD */
/* Constant Gen - Indexed; Ex: MOV #C, 0x0(Rd) */ /* -1, 8 */
/* Constant Gen - Symbolic; Ex: MOV #C, 0xD */ /* -1, 8 */
/* Constant Gen - Absolute; Ex: MOV #C, &0xD */ /* -1, 8 */
else if (as_flag == 3 && ad_flag == 1) {
if (constant_generator_active) { /* Source Constant */
source_value = immediate_constant;
sprintf(asm_operands, "#0x%04X, ", (uint16_t)source_value);
}
else if (source == 0) { /* Source Immediate */
source_value = fetch(emu);
sprintf(hex_str_part, "%04X", (uint16_t) source_value);
strncat(hex_str, hex_str_part, sizeof hex_str);
sprintf(asm_operands, "#0x%04X, ", (uint16_t)source_value);
}
else { /* Source Indirect Auto Increment */
source_value = *get_addr_ptr(*s_reg);
sprintf(asm_operands, "@%s+, ", s_reg_name);
if (!disassemble) {
bw_flag == WORD ? *s_reg += 2 : (*s_reg += 1);
}
}
destination_offset = fetch(emu);
sprintf(hex_str_part, "%04X", (uint16_t) destination_offset);
strncat(hex_str, hex_str_part, sizeof hex_str);
if (destination == 0) { /* Destination Symbolic */
uint16_t virtual_addr = cpu->pc + destination_offset - 2;
destination_addr = get_addr_ptr(virtual_addr);
sprintf(asm_op2, "0x%04X", virtual_addr);
}
else if (destination == 2) { /* Destination Absolute */
destination_addr = get_addr_ptr(destination_offset);
sprintf(asm_op2, "&0x%04X", (uint16_t) destination_offset);
}
else { /* Destination Indexed */
destination_addr = get_addr_ptr(*d_reg + destination_offset);
sprintf(asm_op2, "0x%04X(%s)",
(uint16_t) destination_offset, d_reg_name);
}
strncat(asm_operands, asm_op2, sizeof asm_op2);
}
if (!disassemble) {
switch (opcode) {
/* MOV SOURCE, DESTINATION
* Ex: MOV #4, R6
*
* SOURCE = DESTINATION
*
* The source operand is moved to the destination. The source operand is
* not affected. The previous contents of the destination are lost.
*
*/
case 0x4: {
if (bw_flag == WORD) {
*destination_addr = source_value;
}
else if (bw_flag == BYTE) {
*((uint8_t *) destination_addr) = (uint8_t) source_value;
}
break;
}
/* ADD SOURCE, DESTINATION
* Ex: ADD R5, R4
*
* The source operand is added to the destination operand. The source op
* is not affected. The previous contents of the destination are lost.
*
* DESTINATION = SOURCE + DESTINATION
*
* N: Set if result is negative, reset if positive
* Z: Set if result is zero, reset otherwise
* C: Set if there is a carry from the result, cleared if not
* V: Set if an arithmetic overflow occurs, otherwise reset
*
*/
case 0x5:{
uint16_t original_dst_value = *destination_addr;
if (bw_flag == WORD) {
*destination_addr += source_value;
}
else if (bw_flag == BYTE) {
*((uint8_t *) destination_addr) += (uint8_t) source_value;
}
cpu->sr.zero = is_zero(destination_addr, bw_flag);
cpu->sr.negative = is_negative(destination_addr, bw_flag);
cpu->sr.carry = is_carried(original_dst_value, source_value, bw_flag);
cpu->sr.overflow = is_overflowed(source_value, original_dst_value,
destination_addr, bw_flag);
break;
}
/* ADDC SOURCE, DESTINATION
* Ex: ADDC R5, R4
*
* DESTINATION += (SOURCE + C)
*
* N: Set if result is negative, reset if positive
* Z: Set if result is zero, reset otherwise
* C: Set if there is a carry from the result, cleared if not
* V: Set if an arithmetic overflow occurs, otherwise reset
*
*/
case 0x6:{
uint16_t original_dst_value = *destination_addr;
if (bw_flag == WORD) {
*destination_addr += source_value + cpu->sr.carry;
}
else if (bw_flag == BYTE) {
*((uint8_t *) destination_addr) += (uint8_t) source_value + cpu->sr.carry;
}
cpu->sr.zero = is_zero(destination_addr, bw_flag);
cpu->sr.negative = is_negative(destination_addr, bw_flag);
cpu->sr.carry = is_carried(original_dst_value, source_value, bw_flag);
cpu->sr.overflow = is_overflowed(source_value, original_dst_value,
destination_addr, bw_flag);
break;
}
/* SUBC SOURCE, DESTINATION
* Ex: SUB R4, R5
*
* DST += ~SRC + C
*
* N: Set if result is negative, reset if positive
* Z: Set if result is zero, reset otherwise
* C: Set if there is a carry from the MSB of the result, reset otherwise.
* Set to 1 if no borrow, reset if borrow.
* V: Set if an arithmetic overflow occurs, otherwise reset
*
*
*/
case 0x7:{
int16_t original_dst_value = *destination_addr;
source_value = ~source_value; /* 1's comp */
if (bw_flag == WORD) {
*(int16_t *)destination_addr += source_value + cpu->sr.carry;
}
else if (bw_flag == BYTE) {
*(int8_t *)destination_addr += (int8_t) source_value + cpu->sr.carry;
}
cpu->sr.zero = is_zero(destination_addr, bw_flag);
cpu->sr.negative = is_negative(destination_addr, bw_flag);
cpu->sr.carry = is_carried(original_dst_value, source_value, bw_flag);
cpu->sr.overflow = is_overflowed(source_value, original_dst_value,
destination_addr, bw_flag);
break;
}
/* SUB SOURCE, DESTINATION
* Ex: SUB R4, R5
*
* DST -= SRC
*
* N: Set if result is negative, reset if positive
* Z: Set if result is zero, reset otherwise
* C: Set if there is a carry from the MSB of the result, reset otherwise.
* Set to 1 if no borrow, reset if borrow.
* V: Set if an arithmetic overflow occurs, otherwise reset
* TODO: SUBTRACTION OVERFLOW FLAG ERROR
*/
case 0x8:{
int16_t original_dst_value = *destination_addr;
source_value = ~source_value + 1;
if (bw_flag == WORD) {
*(uint16_t *)destination_addr += source_value;
}
else if (bw_flag == BYTE) {
*(uint8_t *)destination_addr += (uint8_t) source_value;
}
cpu->sr.zero = is_zero(destination_addr, bw_flag);
cpu->sr.negative = is_negative(destination_addr, bw_flag);
if ( is_carried(~source_value, 1, bw_flag) ||
is_carried(original_dst_value, source_value, bw_flag) ) {
cpu->sr.carry = true;
}
cpu->sr.overflow = is_overflowed(source_value, original_dst_value,
destination_addr, bw_flag);
break;
}
/* CMP SOURCE, DESTINATION
*
* N: Set if result is negative, reset if positive (src ≥ dst)
* Z: Set if result is zero, reset otherwise (src = dst)
* C: Set if there is a carry from the MSB of the result, reset otherwise
* V: Set if an arithmetic overflow occurs, otherwise reset
* TODO: Fix overflow error
*/
case 0x9:{
int16_t original_dst_value = *destination_addr;
uint16_t unsigned_source_value = ((uint16_t)~source_value + 1);
int16_t result;
bool early_carry = is_carried((uint16_t)~source_value, 1, bw_flag);
if (bw_flag == WORD) {
result = *destination_addr + (uint16_t) unsigned_source_value;
}
else if (bw_flag == BYTE) {
result = *(uint8_t *)destination_addr + (uint8_t)unsigned_source_value;
}
cpu->sr.negative = is_negative(&result, bw_flag);
cpu->sr.zero = is_zero(&result, bw_flag);
/* Check if the carry happens durring conversion to 2's comp */
if (! early_carry) {
cpu->sr.carry = is_carried(original_dst_value,
unsigned_source_value, bw_flag);
}
else {
cpu->sr.carry = true;
}
cpu->sr.overflow = is_overflowed(unsigned_source_value,
original_dst_value, &result, bw_flag);
break;
}
/* DADD SOURCE, DESTINATION
*
*/
case 0xA:{
if (bw_flag == WORD) {
}
else if (bw_flag == BYTE) {
}
break;
}
/* BIT SOURCE, DESTINATION
*
* N: Set if MSB of result is set, reset otherwise
* Z: Set if result is zero, reset otherwise
* C: Set if result is not zero, reset otherwise (.NOT. Zero)
* V: Reset
*/
case 0xB:{
if (bw_flag == WORD) {
uint16_t result = ((uint16_t) source_value) & (*destination_addr);
cpu->sr.zero = (result == 0);
cpu->sr.negative = result >> 15;
cpu->sr.carry = (result != 0);
}
else if (bw_flag == BYTE) {
uint8_t result =
((uint8_t) source_value) & (*(uint8_t *) destination_addr);
cpu->sr.zero = (result == 0);
cpu->sr.negative = result >> 7;
cpu->sr.carry = (result != 0);
}
cpu->sr.overflow = false;
break;
}
