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Some 8bit commands *do* only update the lower 8 bit while not changing

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the 8 upper bits.
This commit is contained in:
folkert van heusden 2022-03-24 21:39:41 +01:00
parent ac96e9afe5
commit 1443b62fcc
2 changed files with 30 additions and 14 deletions
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43
cpu.cpp
View file

@ -68,6 +68,21 @@ void cpu::setRegister(const int nr, const bool prev_mode, const uint16_t value)
}
}
void cpu::setRegisterLowByte(const int nr, const bool word_mode, const uint16_t value) // prev_mode == false
{
if (word_mode) {
uint16_t v = getRegister(nr, false);
v &= 0xff00;
v |= value;
setRegister(nr, false, v);
}
else {
setRegister(nr, false, value);
}
}
void cpu::addRegister(const int nr, const bool prev_mode, const uint16_t value)
{
if (nr < 6)
@ -378,7 +393,7 @@ bool cpu::double_operand_instructions(const uint16_t instr)
uint16_t result = b -> readWord(a) & ~src_value;
if (dst_mode == 0)
putGAM(dst_mode, dst_reg, word_mode, result, false);
setRegisterLowByte(dst_reg, word_mode, result);
else
b -> write(a, word_mode, result);
@ -396,7 +411,7 @@ bool cpu::double_operand_instructions(const uint16_t instr)
uint16_t result = b -> readWord(a) | src_value;
if (dst_mode == 0)
putGAM(dst_mode, dst_reg, word_mode, result, false);
setRegisterLowByte(dst_reg, word_mode, result);
else
b -> write(a, word_mode, result);
@ -680,7 +695,7 @@ bool cpu::single_operand_instructions(const uint16_t instr)
setPSW_c(true);
if (dst_mode == 0)
putGAM(dst_mode, dst_reg, word_mode, v, false);
setRegisterLowByte(dst_reg, word_mode, v);
else
b -> write(a, word_mode, v);
@ -695,7 +710,7 @@ bool cpu::single_operand_instructions(const uint16_t instr)
setPSW_z(vl == 0);
setPSW_v(word_mode ? v == 0x7f : v == 0x7fff);
if (dst_mode == 0)
putGAM(dst_mode, dst_reg, word_mode, vl, false);
setRegisterLowByte(dst_reg, word_mode, vl);
else
b -> write(a, word_mode, vl);
break;
@ -711,7 +726,7 @@ bool cpu::single_operand_instructions(const uint16_t instr)
setPSW_v(word_mode ? v == 0x80 : v == 0x8000);
if (dst_mode == 0)
putGAM(dst_mode, dst_reg, word_mode, vl, false);
setRegisterLowByte(dst_reg, word_mode, vl);
else
b -> write(a, word_mode, vl);
break;
@ -722,7 +737,7 @@ bool cpu::single_operand_instructions(const uint16_t instr)
uint16_t v = b -> read(a, word_mode);
int32_t vl = word_mode ? uint8_t(-int8_t(v)) : -int16_t(v);
if (dst_mode == 0)
putGAM(dst_mode, dst_reg, word_mode, vl, false);
setRegisterLowByte(dst_reg, word_mode, vl);
else
b -> write(a, word_mode, vl);
setPSW_n(SIGN(vl, word_mode));
@ -738,7 +753,7 @@ bool cpu::single_operand_instructions(const uint16_t instr)
uint16_t new_ = org + getPSW_c();
if (dst_mode == 0)
putGAM(dst_mode, dst_reg, word_mode, new_, false);
setRegisterLowByte(dst_reg, word_mode, new_);
else
b -> write(a, word_mode, new_);
@ -755,7 +770,7 @@ bool cpu::single_operand_instructions(const uint16_t instr)
int32_t vl = (v - getPSW_c()) & (word_mode ? 0xff : 0xffff);
if (dst_mode == 0)
putGAM(dst_mode, dst_reg, word_mode, vl, false);
setRegisterLowByte(dst_reg, word_mode, vl);
else
b -> write(a, word_mode, vl);
@ -788,14 +803,14 @@ bool cpu::single_operand_instructions(const uint16_t instr)
if (word_mode) {
temp = (t >> 1) | (getPSW_c() << 7);
if (dst_mode == 0)
putGAM(dst_mode, dst_reg, word_mode, temp, false);
setRegisterLowByte(dst_reg, word_mode, temp);
else
b -> writeByte(a, temp);
}
else {
temp = (t >> 1) | (getPSW_c() << 15);
if (dst_mode == 0)
putGAM(dst_mode, dst_reg, word_mode, temp, false);
setRegisterLowByte(dst_reg, word_mode, temp);
else
b -> writeWord(a, temp);
}
@ -819,7 +834,7 @@ bool cpu::single_operand_instructions(const uint16_t instr)
new_carry = t & 0x80;
temp = ((t << 1) | getPSW_c()) & 0xff;
if (dst_mode == 0)
putGAM(dst_mode, dst_reg, word_mode, temp, false);
setRegisterLowByte(dst_reg, word_mode, temp);
else
b -> writeByte(a, temp);
}
@ -827,7 +842,7 @@ bool cpu::single_operand_instructions(const uint16_t instr)
new_carry = t & 0x8000;
temp = (t << 1) | getPSW_c();
if (dst_mode == 0)
putGAM(dst_mode, dst_reg, word_mode, temp, false);
setRegisterLowByte(dst_reg, word_mode, temp);
else
b -> writeWord(a, temp);
}
@ -855,7 +870,7 @@ bool cpu::single_operand_instructions(const uint16_t instr)
vl |= hb << 15;
if (dst_mode == 0)
putGAM(dst_mode, dst_reg, word_mode, vl, false);
setRegisterLowByte(dst_reg, word_mode, vl);
else
b -> write(a, word_mode, vl);
@ -874,7 +889,7 @@ bool cpu::single_operand_instructions(const uint16_t instr)
setPSW_c(word_mode ? vl & 0x80 : vl & 0x8000);
setPSW_v(getPSW_n() ^ getPSW_c());
if (dst_mode == 0)
putGAM(dst_mode, dst_reg, word_mode, v, false);
setRegisterLowByte(dst_reg, word_mode, v);
else
b -> write(a, word_mode, v);
break;

1
cpu.h
View file

@ -99,6 +99,7 @@ public:
uint16_t getStackPointer(const int which) const { assert(which >= 0 && which < 4); return sp[which]; }
uint16_t getPC() const { return pc; }
void setRegisterLowByte(const int nr, const bool prev_mode, const uint16_t value);
void setRegister(const bool user, const int nr, const uint16_t value) { regs0_5[user][nr] = value; }
void setStackPointer(const int which, const uint16_t value) { assert(which >= 0 && which < 4); sp[which] = value; }
void setPC(const uint16_t value) { pc = value; }