From 6540609c35bd58fa80d64ba782f31d1ad44eb042 Mon Sep 17 00:00:00 2001 From: Benjamin Valentin Date: Mon, 9 Mar 2020 18:34:06 +0100 Subject: [PATCH] cpu/sam0_common: gpio: save a few cycles in isr_eic() Don't iterate over all bits in the GPIO status register, instead just loop as many times as there are set bits. --- cpu/sam0_common/periph/gpio.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) diff --git a/cpu/sam0_common/periph/gpio.c b/cpu/sam0_common/periph/gpio.c index e721d75a72..f8c7c5e49b 100644 --- a/cpu/sam0_common/periph/gpio.c +++ b/cpu/sam0_common/periph/gpio.c @@ -322,12 +322,18 @@ void gpio_irq_disable(gpio_t pin) void isr_eic(void) { - for (unsigned i = 0; i < NUMOF_IRQS; i++) { - if (_EIC->INTFLAG.reg & (1 << i)) { - _EIC->INTFLAG.reg = (1 << i); - gpio_config[i].cb(gpio_config[i].arg); - } + /* read & clear interrupt flags */ + uint32_t state = _EIC->INTFLAG.reg; + state &= (1 << NUMOF_IRQS) - 1; + _EIC->INTFLAG.reg = state; + + /* execute interrupt callbacks */ + while (state) { + unsigned pin = 8 * sizeof(state) - __builtin_clz(state) - 1; + state &= ~(1 << pin); + gpio_config[pin].cb(gpio_config[pin].arg); } + cortexm_isr_end(); }