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#include <stdbool.h>
#include <util/delay.h>
#include <avr/io.h>
#include "adb.h"
static inline void data_lo(void);
static inline void data_hi(void);
static inline bool data_in(void);
#ifdef ADB_PSW_BIT
static inline void psw_lo(void);
static inline void psw_hi(void);
static inline bool psw_in(void);
#endif
static inline void attention(void);
static inline void place_bit0(void);
static inline void place_bit1(void);
static inline void send_byte(uint8_t data);
static inline bool read_bit(void);
static inline uint8_t read_byte(void);
static inline uint8_t wait_data_lo(uint8_t us);
static inline uint8_t wait_data_hi(uint8_t us);
void adb_host_init(void)
{
data_hi();
#ifdef ADB_PSW_BIT
psw_hi();
#endif
}
#ifdef ADB_PSW_BIT
bool adb_host_psw(void)
{
return psw_in();
}
#endif
uint16_t adb_host_kbd_recv(void)
{
uint16_t data = 0;
attention();
send_byte(0x2C); // Addr:Keyboard(0010), Cmd:Talk(11), Register0(00)
place_bit0(); // Stopbit(0)
if (!wait_data_lo(0xFF)) // Tlt/Stop to Start(140-260us)
return 0; // No data to send
if (!read_bit()) // Startbit(1)
return -2;
data = read_byte();
data = (data<<8) | read_byte();
if (read_bit()) // Stopbit(0)
return -3;
return data;
}
// send state of LEDs
void adb_host_kbd_led(uint8_t led)
{
attention();
send_byte(0x2A); // Addr:Keyboard(0010), Cmd:Listen(10), Register2(10)
place_bit0(); // Stopbit(0)
_delay_us(200); // Tlt/Stop to Start
place_bit1(); // Startbit(1)
send_byte(0); // send upper byte (not used)
send_byte(led&0x07); // send lower byte (bit2: ScrollLock, bit1: CapsLock, bit0: NumLock)
place_bit0(); // Stopbit(0);
}
static inline void data_lo()
{
ADB_DDR |= (1<<ADB_DATA_BIT);
ADB_PORT &= ~(1<<ADB_DATA_BIT);
}
static inline void data_hi()
{
ADB_PORT |= (1<<ADB_DATA_BIT);
ADB_DDR &= ~(1<<ADB_DATA_BIT);
}
static inline bool data_in()
{
ADB_PORT |= (1<<ADB_DATA_BIT);
ADB_DDR &= ~(1<<ADB_DATA_BIT);
return ADB_PIN&(1<<ADB_DATA_BIT);
}
#ifdef ADB_PSW_BIT
static inline void psw_lo()
{
ADB_DDR |= (1<<ADB_PSW_BIT);
ADB_PORT &= ~(1<<ADB_PSW_BIT);
}
static inline void psw_hi()
{
ADB_PORT |= (1<<ADB_PSW_BIT);
ADB_DDR &= ~(1<<ADB_PSW_BIT);
}
static inline bool psw_in()
{
ADB_PORT |= (1<<ADB_PSW_BIT);
ADB_DDR &= ~(1<<ADB_PSW_BIT);
return ADB_PIN&(1<<ADB_PSW_BIT);
}
#endif
static inline void attention(void)
{
data_lo();
_delay_us(700);
place_bit1();
}
static inline void place_bit0(void)
{
data_lo();
_delay_us(65);
data_hi();
_delay_us(35);
}
static inline void place_bit1(void)
{
data_lo();
_delay_us(35);
data_hi();
_delay_us(65);
}
static inline void send_byte(uint8_t data)
{
for (int i = 0; i < 8; i++) {
if (data&(0x80>>i))
place_bit1();
else
place_bit0();
}
}
static inline bool read_bit(void)
{
// ADB Bit Cells
//
// bit0: ______~~~
// 65 :35us
//
// bit1: ___~~~~~~
// 35 :65us
//
// bit0 low time: 60-70% of bit cell(42-91us)
// bit1 low time: 30-40% of bit cell(21-52us)
// bit cell time: 70-130us
// [from Apple IIgs Hardware Reference Second Edition]
//
// After 55us if data line is low/high then bit is 0/1.
// Too simple to rely on?
bool bit;
wait_data_lo(75); // wait the beginning of bit cell
_delay_us(55);
bit = data_in();
wait_data_hi(36); // wait high part of bit cell
return bit;
}
static inline uint8_t read_byte(void)
{
uint8_t data = 0;
for (int i = 0; i < 8; i++) {
data <<= 1;
if (read_bit())
data = data | 1;
}
return data;
}
static inline uint8_t wait_data_lo(uint8_t us)
{
while (data_in() && us) {
_delay_us(1);
us--;
}
return us;
}
static inline uint8_t wait_data_hi(uint8_t us)
{
while (!data_in() && us) {
_delay_us(1);
us--;
}
return us;
}
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