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fix(ulp_riscv): Fix a delay function to handle small delays correctly

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Fixed ulp_riscv_delay_cycles function

Closes https://github.com/espressif/esp-idf/issues/16891
This commit is contained in:
Konstantin Kondrashov
2025-07-18 14:19:24 +03:00
parent a0f071f7ff
commit e9cae6c805
1 changed files with 10 additions and 6 deletions
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14
components/ulp/ulp_riscv/ulp_core/include/ulp_riscv_utils.h
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@@ -1,5 +1,5 @@
/*
* SPDX-FileCopyrightText: 2015-2024 Espressif Systems (Shanghai) CO LTD
* SPDX-FileCopyrightText: 2015-2025 Espressif Systems (Shanghai) CO LTD
*
* SPDX-License-Identifier: Apache-2.0
*/
@@ -92,14 +92,18 @@ void ulp_riscv_timer_resume(void);
/**
* @brief Makes the co-processor busy wait for a certain number of cycles
*
* @note This function is not accurate for delays shorter than 20 cycles,
* as the function's own overhead may exceed the requested delay.
*
* @param cycles Number of cycles to busy wait
*/
void static inline ulp_riscv_delay_cycles(uint32_t cycles)
{
uint32_t start = ULP_RISCV_GET_CCOUNT();
/* Off with an estimate of cycles in this function to improve accuracy */
uint32_t end = start + cycles - 20;
if (cycles <= 20) { // the estimate of cycles for this function
return;
}
/* Off with the estimate of cycles to improve accuracy */
uint32_t end = ULP_RISCV_GET_CCOUNT() + cycles - 20;
while (ULP_RISCV_GET_CCOUNT() < end) {
/* Wait */
}