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CLRB fix

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folkert van heusden 2022-03-30 23:21:01 +02:00
parent 00e4234ff5
commit 40d22393db
1 changed files with 9 additions and 5 deletions
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14
cpu.cpp
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@ -659,8 +659,15 @@ bool cpu::single_operand_instructions(const uint16_t instr)
}
case 0b000101000: { // CLR/CLRB
if (dst_mode == 0)
putGAM(dst_mode, dst_reg, word_mode, 0, false);
if (dst_mode == 0) {
uint16_t r = 0;
// CLRB only clears the least significant byte
if (word_mode)
r = getGAM(dst_mode, dst_reg, false, false) & 0xff00;
putGAM(dst_mode, dst_reg, false, r, false);
}
else {
uint16_t a = getGAMAddress(dst_mode, dst_reg, word_mode, false);
@ -1222,8 +1229,6 @@ std::pair<std::string, int> cpu::addressing_to_string(const uint8_t mode_registe
#if !defined(ESP32)
assert(mode_register < 64);
int pc_offset = 0;
uint16_t next_word = b->readWord(pc & 65535);
int reg = mode_register & 7;
@ -1384,7 +1389,6 @@ void cpu::disassemble()
else if (do_opcode == 0b111) {
std::string src_text = format("R%d", (instruction >> 6) & 7);
auto dst_text = addressing_to_string(dst_register, (pc + 2) & 65535);
uint8_t dst = instruction & 63;
switch(ado_opcode) { // additional double operand
case 0: