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made sure SWAB implementation no longer confuses programmer

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folkert van heusden 2022-03-24 22:29:04 +01:00
parent 1443b62fcc
commit 21221e1635
1 changed files with 20 additions and 24 deletions
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44
cpu.cpp
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@ -74,6 +74,8 @@ void cpu::setRegisterLowByte(const int nr, const bool word_mode, const uint16_t
uint16_t v = getRegister(nr, false); uint16_t v = getRegister(nr, false);
v &= 0xff00; v &= 0xff00;
assert(value < 256);
v |= value; v |= value;
setRegister(nr, false, v); setRegister(nr, false, v);
@ -343,15 +345,11 @@ bool cpu::double_operand_instructions(const uint16_t instr)
switch(operation) { switch(operation) {
case 0b001: { // MOV/MOVB Move Word/Byte case 0b001: { // MOV/MOVB Move Word/Byte
uint16_t src_value = getGAM(src_mode, src_reg, word_mode, false); uint16_t src_value = getGAM(src_mode, src_reg, word_mode, false);
if (word_mode) {
if (dst_mode == 0) if (word_mode && dst_mode == 0)
setRegister(dst_reg, false, int8_t(src_value)); // int8_t: sign extension setRegister(dst_reg, false, int8_t(src_value)); // int8_t: sign extension
else else
putGAM(dst_mode, dst_reg, word_mode, src_value, false);
}
else {
putGAM(dst_mode, dst_reg, word_mode, src_value, false); putGAM(dst_mode, dst_reg, word_mode, src_value, false);
}
setPSW_n(SIGN(src_value, word_mode)); setPSW_n(SIGN(src_value, word_mode));
setPSW_z(src_value == 0); setPSW_z(src_value == 0);
@ -390,7 +388,7 @@ bool cpu::double_operand_instructions(const uint16_t instr)
uint16_t src_value = getGAM(src_mode, src_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 a = getGAMAddress(dst_mode, dst_reg, word_mode, false);
uint16_t result = b -> readWord(a) & ~src_value; uint16_t result = b->read(a, word_mode) & ~src_value;
if (dst_mode == 0) if (dst_mode == 0)
setRegisterLowByte(dst_reg, word_mode, result); setRegisterLowByte(dst_reg, word_mode, result);
@ -408,7 +406,7 @@ bool cpu::double_operand_instructions(const uint16_t instr)
uint16_t src_value = getGAM(src_mode, src_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 a = getGAMAddress(dst_mode, dst_reg, word_mode, false);
uint16_t result = b -> readWord(a) | src_value; uint16_t result = b->read(a, word_mode) | src_value;
if (dst_mode == 0) if (dst_mode == 0)
setRegisterLowByte(dst_reg, word_mode, result); setRegisterLowByte(dst_reg, word_mode, result);
@ -424,8 +422,8 @@ bool cpu::double_operand_instructions(const uint16_t instr)
case 0b110: { // ADD/SUB Add/Subtract Word case 0b110: { // ADD/SUB Add/Subtract Word
int16_t src_value = getGAM(src_mode, src_reg, false, false); int16_t src_value = getGAM(src_mode, src_reg, false, false);
uint16_t da = getGAMAddress(dst_mode, dst_reg, false, false); uint16_t dst_addr = getGAMAddress(dst_mode, dst_reg, false, false);
int16_t dst_value = b -> readWord(da); int16_t dst_value = b->readWord(dst_addr);
int16_t result = 0; int16_t result = 0;
if (instr & 0x8000) { if (instr & 0x8000) {
@ -445,7 +443,7 @@ bool cpu::double_operand_instructions(const uint16_t instr)
if (dst_mode == 0) if (dst_mode == 0)
setRegister(dst_reg, false, result); setRegister(dst_reg, false, result);
else else
b -> writeWord(da, result); b->writeWord(dst_addr, result);
return true; return true;
} }
@ -634,28 +632,26 @@ bool cpu::single_operand_instructions(const uint16_t instr)
if (word_mode) // handled elsewhere if (word_mode) // handled elsewhere
return false; return false;
else { else {
uint8_t t1 = 0, t2 = 0; uint16_t v = 0;
if (dst_mode == 0) { if (dst_mode == 0) {
uint16_t t = getRegister(dst_reg, false); v = getRegister(dst_reg, false);
t1 = t >> 8; v = ((v & 0xff) << 8) | (v >> 8);
t2 = t & 255;
setRegister(dst_reg, false, (t2 << 8) | t1); setRegister(dst_reg, false, v);
} }
else { else {
uint16_t a = getGAMAddress(dst_mode, dst_reg, word_mode, false); uint16_t a = getGAMAddress(dst_mode, dst_reg, word_mode, false);
v = b->readWord(a);
t1 = b -> readByte(a); v = ((v & 0xff) << 8) | (v >> 8);
t2 = b -> readByte(a + 1);
b -> writeByte(a, t2); b->writeWord(a, v);
b -> writeByte(a + 1, t1);
} }
setPSW_n(t1 & 0x80); setPSW_n(v & 0x80);
setPSW_z(t1 == 0); setPSW_z((v & 0xff) == 0);
setPSW_v(false); setPSW_v(false);
setPSW_c(false); setPSW_c(false);
} }