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i2c_software: reduce gpio calls count

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gpio reset calls are heavy.
gpio state are persistent between calls.
Drop useless calls.
Avoid calls if SDA does not changed.

Signed-off-by: Timofey Titovets <nefelim4ag@gmail.com>
This commit is contained in:
Timofey Titovets 2025-04-09 01:45:52 +02:00 committed by KevinOConnor
parent 8ab12c86bf
commit 841adcfff7
1 changed files with 12 additions and 10 deletions
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22
src/i2c_software.c
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@ -65,9 +65,7 @@ i2c_delay(uint32_t ticks)
static void
i2c_software_send_ack(struct i2c_software *is, const uint8_t ack)
{
if (ack) {
gpio_in_reset(is->sda_in, 1);
} else {
if (!ack) {
gpio_out_reset(is->sda_out, 0);
}
i2c_delay(is->ticks);
@ -77,27 +75,32 @@ i2c_software_send_ack(struct i2c_software *is, const uint8_t ack)
}
static uint8_t
i2c_software_read_ack(struct i2c_software *is)
i2c_software_read_ack(struct i2c_software *is, uint_fast8_t state)
{
uint8_t nack = 0;
gpio_in_reset(is->sda_in, 1);
if (state == 0)
gpio_in_reset(is->sda_in, 1);
i2c_delay(is->ticks);
gpio_in_reset(is->scl_in, 1);
nack = gpio_in_read(is->sda_in);
i2c_delay(is->ticks);
gpio_out_reset(is->scl_out, 0);
gpio_in_reset(is->sda_in, 1);
return nack;
}
static int
i2c_software_send_byte(struct i2c_software *is, uint8_t b)
{
uint_fast8_t state = 2;
for (uint_fast8_t i = 0; i < 8; i++) {
if (b & 0x80) {
gpio_in_reset(is->sda_in, 1);
if (state != 1)
gpio_in_reset(is->sda_in, 1);
state = 1;
} else {
gpio_out_reset(is->sda_out, 0);
if (state > 0)
gpio_out_reset(is->sda_out, 0);
state = 0;
}
b <<= 1;
i2c_delay(is->ticks);
@ -106,7 +109,7 @@ i2c_software_send_byte(struct i2c_software *is, uint8_t b)
gpio_out_reset(is->scl_out, 0);
}
if (i2c_software_read_ack(is)) {
if (i2c_software_read_ack(is, state)) {
return I2C_BUS_NACK;
}
@ -126,7 +129,6 @@ i2c_software_read_byte(struct i2c_software *is, uint8_t remaining)
b |= gpio_in_read(is->sda_in);
gpio_out_reset(is->scl_out, 0);
}
gpio_in_reset(is->sda_in, 1);
i2c_software_send_ack(is, remaining == 0);
return b;
}