445 lines
11 KiB
C
445 lines
11 KiB
C
/*
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* WARNING: be careful changing this code, it is very timing dependent
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*/
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#ifndef F_CPU
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#define F_CPU 16000000
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#endif
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#include <avr/io.h>
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#include <avr/interrupt.h>
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#include <util/delay.h>
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#include <stddef.h>
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#include <stdbool.h>
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#include "serial.h"
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//#include <pro_micro.h>
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#ifdef USE_SERIAL
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#ifndef SERIAL_USE_MULTI_TRANSACTION
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/* --- USE Simple API (OLD API, compatible with let's split serial.c) */
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#if SERIAL_SLAVE_BUFFER_LENGTH > 0
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uint8_t volatile serial_slave_buffer[SERIAL_SLAVE_BUFFER_LENGTH] = {0};
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#endif
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#if SERIAL_MASTER_BUFFER_LENGTH > 0
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uint8_t volatile serial_master_buffer[SERIAL_MASTER_BUFFER_LENGTH] = {0};
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#endif
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uint8_t volatile status0 = 0;
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SSTD_t transactions[] = {
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{ (uint8_t *)&status0,
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#if SERIAL_MASTER_BUFFER_LENGTH > 0
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sizeof(serial_master_buffer), (uint8_t *)serial_master_buffer,
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#else
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0, (uint8_t *)NULL,
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#endif
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#if SERIAL_SLAVE_BUFFER_LENGTH > 0
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sizeof(serial_slave_buffer), (uint8_t *)serial_slave_buffer
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#else
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0, (uint8_t *)NULL,
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#endif
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}
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};
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void serial_master_init(void)
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{ soft_serial_initiator_init(transactions); }
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void serial_slave_init(void)
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{ soft_serial_target_init(transactions); }
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// 0 => no error
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// 1 => slave did not respond
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// 2 => checksum error
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int serial_update_buffers()
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{ return soft_serial_transaction(); }
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#endif // Simple API (OLD API, compatible with let's split serial.c)
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#define ALWAYS_INLINE __attribute__((always_inline))
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#define NO_INLINE __attribute__((noinline))
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#define _delay_sub_us(x) __builtin_avr_delay_cycles(x)
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// Serial pulse period in microseconds.
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#define TID_SEND_ADJUST 14
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#define SELECT_SERIAL_SPEED 1
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#if SELECT_SERIAL_SPEED == 0
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// Very High speed
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#define SERIAL_DELAY 4 // micro sec
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#define READ_WRITE_START_ADJUST 33 // cycles
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#define READ_WRITE_WIDTH_ADJUST 3 // cycles
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#elif SELECT_SERIAL_SPEED == 1
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// High speed
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#define SERIAL_DELAY 6 // micro sec
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#define READ_WRITE_START_ADJUST 30 // cycles
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#define READ_WRITE_WIDTH_ADJUST 3 // cycles
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#elif SELECT_SERIAL_SPEED == 2
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// Middle speed
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#define SERIAL_DELAY 12 // micro sec
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#define READ_WRITE_START_ADJUST 30 // cycles
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#define READ_WRITE_WIDTH_ADJUST 3 // cycles
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#elif SELECT_SERIAL_SPEED == 3
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// Low speed
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#define SERIAL_DELAY 24 // micro sec
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#define READ_WRITE_START_ADJUST 30 // cycles
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#define READ_WRITE_WIDTH_ADJUST 3 // cycles
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#elif SELECT_SERIAL_SPEED == 4
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// Very Low speed
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#define SERIAL_DELAY 50 // micro sec
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#define READ_WRITE_START_ADJUST 30 // cycles
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#define READ_WRITE_WIDTH_ADJUST 3 // cycles
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#else
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#error Illegal Serial Speed
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#endif
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#define SERIAL_DELAY_HALF1 (SERIAL_DELAY/2)
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#define SERIAL_DELAY_HALF2 (SERIAL_DELAY - SERIAL_DELAY/2)
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#define SLAVE_INT_WIDTH_US 1
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#ifndef SERIAL_USE_MULTI_TRANSACTION
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#define SLAVE_INT_RESPONSE_TIME SERIAL_DELAY
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#else
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#define SLAVE_INT_ACK_WIDTH_UNIT 2
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#define SLAVE_INT_ACK_WIDTH 4
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#endif
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static SSTD_t *Transaction_table = NULL;
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inline static
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void serial_delay(void) {
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_delay_us(SERIAL_DELAY);
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}
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inline static
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void serial_delay_half1(void) {
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_delay_us(SERIAL_DELAY_HALF1);
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}
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inline static
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void serial_delay_half2(void) {
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_delay_us(SERIAL_DELAY_HALF2);
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}
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inline static void serial_output(void) ALWAYS_INLINE;
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inline static
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void serial_output(void) {
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SERIAL_PIN_DDR |= SERIAL_PIN_MASK;
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}
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// make the serial pin an input with pull-up resistor
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inline static void serial_input_with_pullup(void) ALWAYS_INLINE;
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inline static
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void serial_input_with_pullup(void) {
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SERIAL_PIN_DDR &= ~SERIAL_PIN_MASK;
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SERIAL_PIN_PORT |= SERIAL_PIN_MASK;
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}
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inline static
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uint8_t serial_read_pin(void) {
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return !!(SERIAL_PIN_INPUT & SERIAL_PIN_MASK);
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}
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inline static void serial_low(void) ALWAYS_INLINE;
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inline static
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void serial_low(void) {
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SERIAL_PIN_PORT &= ~SERIAL_PIN_MASK;
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}
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inline static void serial_high(void) ALWAYS_INLINE;
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inline static
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void serial_high(void) {
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SERIAL_PIN_PORT |= SERIAL_PIN_MASK;
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}
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void soft_serial_initiator_init(SSTD_t *sstd_table)
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{
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Transaction_table = sstd_table;
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serial_output();
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serial_high();
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}
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void soft_serial_target_init(SSTD_t *sstd_table)
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{
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Transaction_table = sstd_table;
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serial_input_with_pullup();
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#if SERIAL_PIN_MASK == _BV(PD0)
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// Enable INT0
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EIMSK |= _BV(INT0);
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// Trigger on falling edge of INT0
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EICRA &= ~(_BV(ISC00) | _BV(ISC01));
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#elif SERIAL_PIN_MASK == _BV(PD2)
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// Enable INT2
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EIMSK |= _BV(INT2);
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// Trigger on falling edge of INT2
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EICRA &= ~(_BV(ISC20) | _BV(ISC21));
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#else
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#error unknown SERIAL_PIN_MASK value
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#endif
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}
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// Used by the sender to synchronize timing with the reciver.
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static void sync_recv(void) NO_INLINE;
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static
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void sync_recv(void) {
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for (uint8_t i = 0; i < SERIAL_DELAY*5 && serial_read_pin(); i++ ) {
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}
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// This shouldn't hang if the target disconnects because the
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// serial line will float to high if the target does disconnect.
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while (!serial_read_pin());
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}
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// Used by the reciver to send a synchronization signal to the sender.
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static void sync_send(void)NO_INLINE;
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static
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void sync_send(void) {
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serial_low();
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serial_delay();
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serial_high();
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}
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// Reads a byte from the serial line
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static uint8_t serial_read_chunk(uint8_t *pterrcount, uint8_t bit) NO_INLINE;
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static uint8_t serial_read_chunk(uint8_t *pterrcount, uint8_t bit) {
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uint8_t byte, i, p, pb;
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_delay_sub_us(READ_WRITE_START_ADJUST);
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for( i = 0, byte = 0, p = 0; i < bit; i++ ) {
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serial_delay_half1(); // read the middle of pulses
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if( serial_read_pin() ) {
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byte = (byte << 1) | 1; p ^= 1;
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} else {
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byte = (byte << 1) | 0; p ^= 0;
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}
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_delay_sub_us(READ_WRITE_WIDTH_ADJUST);
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serial_delay_half2();
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}
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/* recive parity bit */
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serial_delay_half1(); // read the middle of pulses
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pb = serial_read_pin();
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_delay_sub_us(READ_WRITE_WIDTH_ADJUST);
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serial_delay_half2();
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*pterrcount += (p != pb)? 1 : 0;
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return byte;
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}
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// Sends a byte with MSB ordering
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void serial_write_chunk(uint8_t data, uint8_t bit) NO_INLINE;
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void serial_write_chunk(uint8_t data, uint8_t bit) {
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uint8_t b, p;
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for( p = 0, b = 1<<(bit-1); b ; b >>= 1) {
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if(data & b) {
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serial_high(); p ^= 1;
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} else {
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serial_low(); p ^= 0;
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}
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serial_delay();
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}
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/* send parity bit */
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if(p & 1) { serial_high(); }
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else { serial_low(); }
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serial_delay();
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serial_low(); // sync_send() / senc_recv() need raise edge
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}
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static void serial_send_packet(uint8_t *buffer, uint8_t size) NO_INLINE;
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static
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void serial_send_packet(uint8_t *buffer, uint8_t size) {
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for (uint8_t i = 0; i < size; ++i) {
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uint8_t data;
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data = buffer[i];
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sync_send();
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serial_write_chunk(data,8);
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}
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}
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static uint8_t serial_recive_packet(uint8_t *buffer, uint8_t size) NO_INLINE;
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static
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uint8_t serial_recive_packet(uint8_t *buffer, uint8_t size) {
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uint8_t pecount = 0;
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for (uint8_t i = 0; i < size; ++i) {
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uint8_t data;
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sync_recv();
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data = serial_read_chunk(&pecount, 8);
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buffer[i] = data;
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}
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return pecount == 0;
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}
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inline static
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void change_sender2reciver(void) {
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sync_send(); //0
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serial_delay_half1(); //1
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serial_low(); //2
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serial_input_with_pullup(); //2
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serial_delay_half1(); //3
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}
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inline static
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void change_reciver2sender(void) {
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sync_recv(); //0
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serial_delay(); //1
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serial_low(); //3
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serial_output(); //3
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serial_delay_half1(); //4
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}
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// interrupt handle to be used by the target device
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ISR(SERIAL_PIN_INTERRUPT) {
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#ifndef SERIAL_USE_MULTI_TRANSACTION
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serial_low();
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serial_output();
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SSTD_t *trans = Transaction_table;
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#else
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// recive transaction table index
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uint8_t tid;
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uint8_t pecount = 0;
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sync_recv();
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tid = serial_read_chunk(&pecount,4);
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if(pecount> 0)
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return;
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serial_delay_half1();
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serial_high(); // response step1 low->high
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serial_output();
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_delay_sub_us(SLAVE_INT_ACK_WIDTH_UNIT*SLAVE_INT_ACK_WIDTH);
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SSTD_t *trans = &Transaction_table[tid];
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serial_low(); // response step2 ack high->low
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#endif
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// target send phase
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if( trans->target2initiator_buffer_size > 0 )
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serial_send_packet((uint8_t *)trans->target2initiator_buffer,
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trans->target2initiator_buffer_size);
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// target switch to input
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change_sender2reciver();
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// target recive phase
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if( trans->initiator2target_buffer_size > 0 ) {
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if (serial_recive_packet((uint8_t *)trans->initiator2target_buffer,
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trans->initiator2target_buffer_size) ) {
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*trans->status = TRANSACTION_ACCEPTED;
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} else {
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*trans->status = TRANSACTION_DATA_ERROR;
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}
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} else {
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*trans->status = TRANSACTION_ACCEPTED;
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}
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sync_recv(); //weit initiator output to high
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}
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/////////
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// start transaction by initiator
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//
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// int soft_serial_transaction(int sstd_index)
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//
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// Returns:
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// TRANSACTION_END
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// TRANSACTION_NO_RESPONSE
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// TRANSACTION_DATA_ERROR
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// this code is very time dependent, so we need to disable interrupts
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#ifndef SERIAL_USE_MULTI_TRANSACTION
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int soft_serial_transaction(void) {
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SSTD_t *trans = Transaction_table;
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#else
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int soft_serial_transaction(int sstd_index) {
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SSTD_t *trans = &Transaction_table[sstd_index];
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#endif
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cli();
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// signal to the target that we want to start a transaction
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serial_output();
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serial_low();
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_delay_us(SLAVE_INT_WIDTH_US);
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#ifndef SERIAL_USE_MULTI_TRANSACTION
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// wait for the target response
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serial_input_with_pullup();
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_delay_us(SLAVE_INT_RESPONSE_TIME);
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// check if the target is present
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if (serial_read_pin()) {
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// target failed to pull the line low, assume not present
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serial_output();
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serial_high();
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*trans->status = TRANSACTION_NO_RESPONSE;
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sei();
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return TRANSACTION_NO_RESPONSE;
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}
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#else
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// send transaction table index
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sync_send();
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_delay_sub_us(TID_SEND_ADJUST);
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serial_write_chunk(sstd_index, 4);
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serial_delay_half1();
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// wait for the target response (step1 low->high)
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serial_input_with_pullup();
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while( !serial_read_pin() ) {
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_delay_sub_us(2);
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}
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// check if the target is present (step2 high->low)
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for( int i = 0; serial_read_pin(); i++ ) {
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if (i > SLAVE_INT_ACK_WIDTH + 1) {
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// slave failed to pull the line low, assume not present
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serial_output();
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serial_high();
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*trans->status = TRANSACTION_NO_RESPONSE;
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sei();
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return TRANSACTION_NO_RESPONSE;
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}
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_delay_sub_us(SLAVE_INT_ACK_WIDTH_UNIT);
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}
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#endif
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// initiator recive phase
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// if the target is present syncronize with it
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if( trans->target2initiator_buffer_size > 0 ) {
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if (!serial_recive_packet((uint8_t *)trans->target2initiator_buffer,
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trans->target2initiator_buffer_size) ) {
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serial_output();
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serial_high();
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*trans->status = TRANSACTION_DATA_ERROR;
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sei();
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return TRANSACTION_DATA_ERROR;
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}
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}
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// initiator switch to output
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change_reciver2sender();
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// initiator send phase
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if( trans->initiator2target_buffer_size > 0 ) {
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serial_send_packet((uint8_t *)trans->initiator2target_buffer,
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trans->initiator2target_buffer_size);
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}
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// always, release the line when not in use
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sync_send();
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*trans->status = TRANSACTION_END;
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sei();
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return TRANSACTION_END;
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}
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#ifdef SERIAL_USE_MULTI_TRANSACTION
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int soft_serial_get_and_clean_status(int sstd_index) {
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SSTD_t *trans = &Transaction_table[sstd_index];
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cli();
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int retval = *trans->status;
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*trans->status = 0;;
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sei();
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return retval;
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}
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#endif
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#endif
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