Lib: Util: String conversion API

Adds string conversion API.
Implements basic string to parameter convertion functions.

Signed-off-by: Anders Storrø <[email protected]>

Author: Andrewpini

include/sys/string_conv.h

@@ -0,0 +1,62 @@
+/*
+ * Copyright (c) 2022 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#ifndef ZEPHYR_INCLUDE_SYS_STRING_CONV_H__
+#define ZEPHYR_INCLUDE_SYS_STRING_CONV_H__
+
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief Convert string to long param.
+ *
+ * @note On failure the passed value reference will not be altered.
+ *
+ * @param str Input string
+ * @param val Converted value
+ *
+ * @return 0 on success.
+ * @return -EINVAL on invalid string input.
+ * @return -ERANGE if numeric string input is to large to convert.
+ */
+int string_conv_str2long(const char *str, long *val);
+
+/**
+ * @brief Convert string to unsigned long param.
+ *
+ * @note On failure the passed value reference will not be altered.
+ *
+ * @param str Input string
+ * @param val Converted value
+ *
+ * @return 0 on success.
+ * @return -EINVAL on invalid string input.
+ * @return -ERANGE if numeric string input is to large to convert.
+ */
+int string_conv_str2ulong(const char *str, unsigned long *val);
+
+/**
+ * @brief Convert string to double param.
+ *
+ * @note On failure the passed value reference will not be altered.
+ *
+ * @param str Input string
+ * @param val Converted value
+ *
+ * @return 0 on success.
+ * @return -EINVAL on invalid string input.
+ * @return -ERANGE if numeric string input is to large to convert.
+ */
+int string_conv_str2dbl(const char *str, double *val);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* ZEPHYR_INCLUDE_SYS_STRING_CONV_H__ */

lib/util/CMakeLists.txt

@@ -1,3 +1,4 @@
 # SPDX-License-Identifier: Apache-2.0
 
 add_subdirectory_ifdef(CONFIG_FNMATCH		fnmatch)
+add_subdirectory(string_conv)

lib/util/string_conv/CMakeLists.txt

@@ -0,0 +1,6 @@
+# Copyright (c) 2022 Nordic Semiconductor
+#
+# SPDX-License-Identifier: Apache-2.0
+# #
+
+zephyr_sources(string_conv.c)

lib/util/string_conv/string_conv.c

@@ -0,0 +1,176 @@
+/*
+ * Copyright (c) 2022 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <ctype.h>
+#include <string.h>
+#include <stdlib.h>
+#include <errno.h>
+
+static size_t whitespace_trim(char *out, size_t len, const char *str)
+{
+	if (len == 0) {
+		return 0;
+	}
+
+	const char *end;
+	size_t out_size;
+
+	while (str[0] == ' ') {
+		str++;
+	}
+
+	if (*str == 0) {
+		*out = 0;
+		return 1;
+	}
+
+	end = str + strlen(str) - 1;
+	while (end > str && (end[0] == ' ')) {
+		end--;
+	}
+	end++;
+
+	out_size = (end - str) + 1;
+
+	if (out_size > len) {
+		return 0;
+	}
+
+	memcpy(out, str, out_size - 1);
+	out[out_size - 1] = 0;
+
+	return out_size;
+}
+
+int string_conv_str2long(char *str, long *val)
+{
+	char trimmed_buf[12] = { 0 };
+	size_t len = whitespace_trim(trimmed_buf, sizeof(trimmed_buf), str);
+
+	if (len < 2) {
+		return -EINVAL;
+	}
+
+	long temp_val;
+	int idx = 0;
+
+	if ((trimmed_buf[0] == '-') || (trimmed_buf[0] == '+')) {
+		idx++;
+	}
+
+	for (int i = idx; i < (len - 1); i++) {
+		if (!isdigit((int)trimmed_buf[i])) {
+			return -EINVAL;
+		}
+	}
+
+	errno = 0;
+	temp_val = strtol(trimmed_buf, NULL, 10);
+
+	if (errno == ERANGE) {
+		return -ERANGE;
+	}
+
+	*val = temp_val;
+	return 0;
+}
+
+int string_conv_str2ulong(char *str, unsigned long *val)
+{
+	char trimmed_buf[12] = { 0 };
+	size_t len = whitespace_trim(trimmed_buf, sizeof(trimmed_buf), str);
+
+	if (len < 2) {
+		return -EINVAL;
+	}
+
+	unsigned long temp_val;
+	int idx = 0;
+
+	if (trimmed_buf[0] == '+') {
+		idx++;
+	}
+
+	for (int i = idx; i < (len - 1); i++) {
+		if (!isdigit((int)trimmed_buf[i])) {
+			return -EINVAL;
+		}
+	}
+
+	errno = 0;
+	temp_val = strtoul(trimmed_buf, NULL, 10);
+
+	if (errno == ERANGE) {
+		return -ERANGE;
+	}
+
+	*val = temp_val;
+	return 0;
+}
+
+int string_conv_str2dbl(const char *str, double *val)
+{
+	char trimmed_buf[22] = { 0 };
+	long decimal;
+	unsigned long frac;
+	double frac_dbl;
+	int err = 0;
+
+	size_t len = whitespace_trim(trimmed_buf, sizeof(trimmed_buf), str);
+
+	if (len < 2) {
+		return -EINVAL;
+	}
+
+	int comma_idx = strcspn(trimmed_buf, ".");
+	int frac_len = strlen(trimmed_buf + comma_idx + 1);
+
+	/* Covers corner case "." input */
+	if (strlen(trimmed_buf) < 2 && trimmed_buf[comma_idx] != 0) {
+		return -EINVAL;
+	}
+
+	trimmed_buf[comma_idx] = 0;
+
+	/* Avoid fractional overflow by losing one precision point */
+	if (frac_len > 9) {
+		trimmed_buf[comma_idx + 10] = 0;
+		frac_len = 9;
+	}
+
+	/* Avoid doing str2long if decimal part is empty */
+	if (trimmed_buf[0] == '\0') {
+		decimal = 0;
+	} else {
+		err = string_conv_str2long(trimmed_buf, &decimal);
+
+		if (err) {
+			return err;
+		}
+	}
+
+	/* Avoid doing str2ulong if fractional part is empty */
+	if ((trimmed_buf + comma_idx + 1)[0] == '\0') {
+		frac = 0;
+	} else {
+		err = string_conv_str2ulong(trimmed_buf + comma_idx + 1, &frac);
+
+		if (err) {
+			return err;
+		}
+	}
+
+	frac_dbl = (double)frac;
+
+	for (int i = 0; i < frac_len; i++) {
+		frac_dbl /= 10;
+	}
+
+	*val = (trimmed_buf[0] == '-') ? ((double)decimal - frac_dbl) :
+					       ((double)decimal + frac_dbl);
+
+	return err;
+}

tests/lib/string_conv/CMakeLists.txt

@@ -0,0 +1,8 @@
+# SPDX-License-Identifier: Apache-2.0
+
+cmake_minimum_required(VERSION 3.20.0)
+find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
+project(string_conv)
+
+FILE(GLOB app_sources src/*.c)
+target_sources(app PRIVATE ${app_sources})

tests/lib/string_conv/prj.conf

@@ -0,0 +1 @@
+CONFIG_ZTEST=y