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core/irrt: add cstr_utils

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lyken 2024-07-26 12:39:59 +08:00
parent 40387b9a66
commit cb2b7bec3e
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1 changed files with 80 additions and 0 deletions

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@ -18,4 +18,84 @@ bool arrays_match(int len, T* as, T* bs) {
}
return true;
}
namespace cstr_utils {
/**
* @brief Return true if `str` is empty.
*/
bool is_empty(const char* str) { return str[0] == '\0'; }
/**
* @brief Implementation of `strcmp()`
*/
int8_t compare(const char* a, const char* b) {
uint32_t i = 0;
while (true) {
if (a[i] < b[i]) {
return -1;
} else if (a[i] > b[i]) {
return 1;
} else {
if (a[i] == '\0') {
return 0;
} else {
i++;
}
}
}
}
/**
* @brief Return true two strings have the same content.
*/
int8_t equal(const char* a, const char* b) { return compare(a, b) == 0; }
/**
* @brief Implementation of `strlen()`.
*/
uint32_t length(const char* str) {
uint32_t length = 0;
while (*str != '\0') {
length++;
str++;
}
return length;
}
/**
* @brief Copy a null-terminated string to a buffer with limited size and guaranteed null-termination.
*
* `dst_max_size` must be greater than 0, otherwise this function has undefined behavior.
*
* This function attempts to copy everything from `src` from `dst`, and *always* null-terminates `dst`.
*
* If the size of `dst` is too small, the final byte (`dst[dst_max_size - 1]`) of `dst` will be set to
* the null terminator.
*
* @param src String to copy from.
* @param dst Buffer to copy string to.
* @param dst_max_size
* Number of bytes of this buffer, including the space needed for the null terminator.
* Must be greater than 0.
* @return If `dst` is too small to contain everything in `src`.
*/
bool copy(const char* src, char* dst, uint32_t dst_max_size) {
for (uint32_t i = 0; i < dst_max_size; i++) {
bool is_last = i + 1 == dst_max_size;
if (is_last && src[i] != '\0') {
dst[i] = '\0';
return false;
}
if (src[i] == '\0') {
dst[i] = '\0';
return true;
}
dst[i] = src[i];
}
__builtin_unreachable();
}
} // namespace cstr_utils
} // namespace