diff options
| -rw-r--r-- | lc3.c | 64 |
1 files changed, 39 insertions, 25 deletions
@@ -131,33 +131,22 @@ uint16_t check_key() FD_ZERO(&fds); FD_SET(0, &fds); tv.tv_sec = 0; - tv.tv_sec = 0; + tv.tv_usec = 0; const int r = select(1, &fds, NULL, NULL, &tv); die(r, "check_key select()"); return 0 != r; } +void update_keyboard() +{ + uint8_t c; + ssize_t r = read(0, &c, 1); + die(r, "read_memory read()"); + memory[MEMORY_KBDR] = (uint16_t) c; +} + uint16_t read_memory(const uint16_t address) { - if (MEMORY_KBSR == address) - { - if (check_key()) - { - memory[MEMORY_KBSR] |= 1u << 15; - uint8_t c; - ssize_t r = read(0, &c, 1); - die(r, "read_memory read()"); - memory[MEMORY_KBDR] = (uint16_t) c; - } - else - { - memory[MEMORY_KBSR] &= ~(1u << 15); - } - } - else if (MEMORY_DSR == address) - { - memory[MEMORY_DSR] = 1u << 15; - } return memory[address]; } @@ -189,13 +178,31 @@ void fire(const uint16_t interrupt, const uint16_t priority) void write_memory(const uint16_t address, const uint16_t value) { - if (MEMORY_DDR == address) + switch (address) { - uint8_t c = (uint8_t) value; - ssize_t r = write(1, &c, 1); - die(r, "write_memory write()"); + case MEMORY_KBSR: + { + memory[MEMORY_KBSR] &= 0x8000; + memory[MEMORY_KBSR] |= value & 0x7fff; + break; + } + case MEMORY_KBDR: + case MEMORY_DSR: + { + break; + } + case MEMORY_DDR: + { + uint8_t c = (uint8_t) value; + ssize_t r = write(1, &c, 1); + die(r, "write_memory write()"); + } // fallthrough + default: + { + memory[address] = value; + break; + } } - memory[address] = value; } void update_cond(const uint16_t reg) @@ -494,6 +501,7 @@ int main(int argc, char ** argv) signal(SIGINT, handle_signal); atexit(restore_terminal); prepare_terminal(); + memory[MEMORY_DSR] = 0x8000; registers[REGISTER_PC] = MEMORY_USER; registers[REGISTER_PSR] |= FLAG_SUP; registers[REGISTER_SSP] = MEMORY_USER; @@ -503,7 +511,13 @@ int main(int argc, char ** argv) step(instruction); if (check_key()) { + update_keyboard(); fire(0x80, 4); + memory[MEMORY_KBSR] |= 0x8000; + } + else + { + memory[MEMORY_KBSR] &= 0x7fff; } } } |