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cleanup of cpu::double_operand_instructions

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folkert van heusden 2022-03-20 20:55:28 +01:00
parent 1ad1b9aa0a
commit 9c8a9f349d
1 changed files with 41 additions and 35 deletions
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76
cpu.cpp
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@ -290,9 +290,9 @@ uint16_t cpu::getGAMAddress(const uint8_t mode, const int reg, const bool word_m
bool cpu::double_operand_instructions(const uint16_t instr)
{
bool word_mode = !!(instr & 0x8000);
const bool word_mode = !!(instr & 0x8000);
uint8_t operation = (instr >> 12) & 7;
const uint8_t operation = (instr >> 12) & 7;
if (operation == 0b000)
return single_operand_instructions(instr);
@ -304,61 +304,61 @@ bool cpu::double_operand_instructions(const uint16_t instr)
const uint8_t src_mode = (src >> 3) & 7;
const uint8_t src_reg = src & 7;
uint16_t src_value = 0;
const uint8_t dst = instr & 63;
const uint8_t dst_mode = (dst >> 3) & 7;
const uint8_t dst_reg = dst & 7;
switch(operation) {
case 0b001: // MOV/MOVB Move Word/Byte
src_value = getGAM(src_mode, src_reg, word_mode, false);
if (word_mode) {
if (dst_mode == 0)
setRegister(dst_reg, false, int8_t(src_value));
else
putGAM(dst_mode, dst_reg, word_mode, src_value, false);
}
else {
putGAM(dst_mode, dst_reg, word_mode, src_value, false);
}
case 0b001: { // MOV/MOVB Move Word/Byte
uint16_t src_value = getGAM(src_mode, src_reg, word_mode, false);
if (word_mode) {
if (dst_mode == 0)
setRegister(dst_reg, false, int8_t(src_value));
else
putGAM(dst_mode, dst_reg, word_mode, src_value, false);
}
else {
putGAM(dst_mode, dst_reg, word_mode, src_value, false);
}
setPSW_n(SIGN(src_value, word_mode));
setPSW_z(src_value == 0);
setPSW_v(false);
setPSW_n(SIGN(src_value, word_mode));
setPSW_z(src_value == 0);
setPSW_v(false);
return true;
return true;
}
case 0b010: { // CMP/CMPB Compare Word/Byte
src_value = getGAM(src_mode, src_reg, word_mode, false);
uint16_t src_value = getGAM(src_mode, src_reg, word_mode, false);
uint16_t dst_value = getGAM(dst_mode, dst_reg, word_mode, false);
uint16_t temp = (src_value - dst_value) & (word_mode ? 0xff : 0xffff);
uint16_t temp = (src_value - dst_value) & (word_mode ? 0xff : 0xffff);
setPSW_n(SIGN(temp, word_mode));
setPSW_z(temp == 0);
setPSW_v(SIGN((src_value ^ dst_value) & (~dst_value ^ temp), word_mode));
setPSW_c(src_value < dst_value);
return true;
}
case 0b011: { // BIT/BITB Bit Test Word/Byte
src_value = getGAM(src_mode, src_reg, word_mode, false);
uint16_t src_value = getGAM(src_mode, src_reg, word_mode, false);
uint16_t dst_value = getGAM(dst_mode, dst_reg, word_mode, false);
uint16_t result = dst_value & src_value;
uint16_t result = dst_value & src_value;
setPSW_n(SIGN(result, word_mode));
setPSW_z(result == 0);
setPSW_v(false);
return true;
}
case 0b100: { // BIC/BICB Bit Clear Word/Byte
src_value = getGAM(src_mode, src_reg, word_mode, false);
uint16_t a = getGAMAddress(dst_mode, dst_reg, word_mode, false);
uint16_t src_value = getGAM(src_mode, src_reg, word_mode, false);
uint16_t a = getGAMAddress(dst_mode, dst_reg, word_mode, false);
uint16_t result = b -> readWord(a) & ~src_value;
uint16_t result = b -> readWord(a) & ~src_value;
if (dst_mode == 0)
putGAM(dst_mode, dst_reg, word_mode, result, false);
@ -368,14 +368,15 @@ bool cpu::double_operand_instructions(const uint16_t instr)
setPSW_n(SIGN(result, word_mode));
setPSW_z(result == 0);
setPSW_v(false);
return true;
}
case 0b101: { // BIS/BISB Bit Set Word/Byte
src_value = getGAM(src_mode, src_reg, word_mode, false);
uint16_t a = getGAMAddress(dst_mode, dst_reg, word_mode, false);
uint16_t src_value = getGAM(src_mode, src_reg, word_mode, false);
uint16_t a = getGAMAddress(dst_mode, dst_reg, word_mode, false);
uint16_t result = b -> readWord(a) | src_value;
uint16_t result = b -> readWord(a) | src_value;
if (dst_mode == 0)
putGAM(dst_mode, dst_reg, word_mode, result, false);
@ -385,14 +386,16 @@ bool cpu::double_operand_instructions(const uint16_t instr)
setPSW_n(SIGN(result, word_mode));
setPSW_z(result == 0);
setPSW_v(false);
return true;
}
case 0b110: { // ADD/SUB Add/Subtract Word
int16_t src_value = getGAM(src_mode, src_reg, false, false);
uint16_t da = getGAMAddress(dst_mode, dst_reg, false, false);
int16_t dst_value = b -> readWord(da);
int16_t result = 0;
int16_t src_value = getGAM(src_mode, src_reg, false, false);
uint16_t da = getGAMAddress(dst_mode, dst_reg, false, false);
int16_t dst_value = b -> readWord(da);
int16_t result = 0;
if (instr & 0x8000) {
result = (dst_value + ~src_value + 1) & 0xffff;
setPSW_v(sign(src_value) != sign(dst_value) && sign(src_value) == sign(result));
@ -403,12 +406,15 @@ bool cpu::double_operand_instructions(const uint16_t instr)
setPSW_v(sign(src_value) == sign(dst_value) && sign(dst_value) != sign(result));
setPSW_c(uint16_t(result) < uint16_t(src_value));
}
setPSW_n(result < 0);
setPSW_z(result == 0);
if (dst_mode == 0)
setRegister(dst_reg, false, result);
else
b -> writeWord(da, result);
return true;
}
}