components/log/src/util.c (ESP-IDF)

/* * SPDX-FileCopyrightText: 2023-2024 Espressif Systems (Shanghai) CO LTD * * SPDX-License-Identifier: Apache-2.0 */ #include <stdint.h> int esp_log_util_cvt(unsigned long long val, long radix, int pad, const char *digits, char *buf) { char *orig_buf = buf; int length = 0; // val = 123 do { *buf++ = digits[val % radix]; val /= radix; length++; } while (val); // 3 2 1 // buf = [0] [1] [2] [3] // length = 3, pad = 6 while (pad > 0 && pad > length) { *buf++ = '0'; length++; } *buf = '\0'; // length = 6 // 3 2 1 0 0 0 \0 // buf = [0] [1] [2] [3] [4] [5] [6] --buf; // reverse the order of characters // 3 2 1 0 0 0 \0 // [0] [1] [2] [3] [4] [5] [6] // orig_buf -- ^ ^ ----- buf while (orig_buf < buf) { char first_char = *orig_buf; char last_char = *buf; *buf-- = first_char; *orig_buf++ = last_char; } // 0 0 0 1 2 3 \0 // buf = [0] [1] [2] [3] [4] [5] [6] return (length); } int esp_log_util_cvt_hex(unsigned long long val, int pad, char *buf) { return esp_log_util_cvt(val, 16, pad, "0123456789abcdef", buf); } int esp_log_util_cvt_dec(unsigned long long val, int pad, char *buf) { return esp_log_util_cvt(val, 10, pad, "0123456789", buf); }