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fix(hal): prevent overflow in fractional clock division

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Co-authored-by: Cursor <cursoragent@cursor.com>
This commit is contained in:
Chen Chen
2026-08-20 14:46:58 +08:00
co-authored by Cursor
parent 71f4b17960
commit a207ed52f9
2 changed files with 15 additions and 6 deletions
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components/hal/hal_utils.c
+6 -5
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@@ -1,5 +1,5 @@
/*
* SPDX-FileCopyrightText: 2023-2024 Espressif Systems (Shanghai) CO LTD
* SPDX-FileCopyrightText: 2023-2026 Espressif Systems (Shanghai) CO LTD
*
* SPDX-License-Identifier: Apache-2.0
*/
@@ -16,7 +16,7 @@
#endif
__attribute__((always_inline))
static inline uint32_t _sub_abs(uint32_t a, uint32_t b)
static inline uint64_t _sub_abs(uint64_t a, uint64_t b)
{
return a > b ? a - b : b - a;
}
@@ -78,9 +78,10 @@ uint32_t hal_utils_calc_clk_div_frac_accurate(const hal_utils_clk_info_t *clk_in
// Carry bit if the decimal is greater than 1.0 - 1.0 / ((max_fract - 1) * 2)
if (freq_error < clk_info->exp_freq_hz - clk_info->exp_freq_hz / (clk_info->max_fract - 1) * 2) {
// Search the closest fraction, time complexity O(n)
for (uint32_t sub = 0, a = 2, b = 0, min = UINT32_MAX; min && a < clk_info->max_fract; a++) {
b = (a * freq_error + clk_info->exp_freq_hz / 2) / clk_info->exp_freq_hz;
sub = _sub_abs(clk_info->exp_freq_hz * b, freq_error * a);
uint64_t min = UINT64_MAX;
for (uint32_t a = 2, b = 0; min && a < clk_info->max_fract; a++) {
b = ((uint64_t)a * freq_error + clk_info->exp_freq_hz / 2) / clk_info->exp_freq_hz;
uint64_t sub = _sub_abs((uint64_t)clk_info->exp_freq_hz * b, (uint64_t)freq_error * a);
if (sub < min) {
div_denom = a;
div_numer = b;