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- #include <stdint.h>
- #include <stdbool.h>
-
- typedef struct {
- // Bit 7: interrupt status, low when interrupt request pending.
- // Bit 6: Parity error
- // Bit 5: Receiver overrun
- // Bit 4: Framing error
- // Bit 3: Clear To Send
- // Bit 2: Data Carrier Detected
- // Bit 1: Transmit Data Register Empty (TDRE)
- // Bit 0: Receive Data Register Full (RDRF)
- // We care about bits 7, 1, 0, maybe 5 later.
- uint8_t status;
- // Bit 7: interrupt enable
- // Bits 6:5: RTS + transmit interrupt enable
- // Bits 4:2: parity + stop bit
- // Bits 1:0: speed divider
- // We don't actually care about any of those except the interrupt enable
- // bits.
- uint8_t control;
- uint8_t rx;
- uint8_t tx;
- // Will be set to true the first time acia_has_irq() is called when IRQ is
- // set. Then, as long as it stays true, acia_has_irq() will return false.
- // When IRQ status is reset, so is in_int.
- bool in_int;
- } ACIA;
-
- void acia_init(ACIA *acia);
- bool acia_has_irq(ACIA *acia);
- bool acia_cantransmit(ACIA *acia);
- bool acia_hastx(ACIA *acia);
- uint8_t acia_read(ACIA *acia);
- void acia_write(ACIA *acia, uint8_t val);
- uint8_t acia_ctl_rd(ACIA *acia);
- void acia_ctl_wr(ACIA *acia, uint8_t val);
- uint8_t acia_data_rd(ACIA *acia);
- void acia_data_wr(ACIA *acia, uint8_t val);
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