X-Git-Url: https://sigrok.org/gitweb/?a=blobdiff_plain;f=src%2Fstrutil.c;h=3d7283b3e846e87338e7af9f97406dc266ccdee6;hb=bee2b0168c087676c1b365861d8c2d4714afa9b9;hp=d817e642d8f1cb9dfb44292c9ea0d8acf11f73af;hpb=89b3a0d8d1cd44e3959a5c332954f34d6e9bd685;p=libsigrok.git

diff --git a/src/strutil.c b/src/strutil.c
index d817e642..3d7283b3 100644
--- a/src/strutil.c
+++ b/src/strutil.c
@@ -211,6 +211,77 @@ SR_PRIV int sr_atof_ascii(const char *str, float *ret)
 	return SR_OK;
 }
 
+/**
+ * Convert a string representation of a numeric value to a @sr_rational. The
+ * conversion is strict and will fail if the complete string does not represent
+ * a valid number. The function sets errno according to the details of the
+ * failure. This version ignores the locale.
+ *
+ * @param str The string representation to convert.
+ * @param ret Pointer to sr_rational where the result of the conversion will be stored.
+ *
+ * @retval SR_OK Conversion successful.
+ * @retval SR_ERR Failure.
+ *
+ * @since 0.5.0
+ */
+SR_API int sr_parse_rational(const char *str, struct sr_rational *ret)
+{
+	char *endptr = NULL;
+	int64_t integral;
+	int64_t fractional = 0;
+	int64_t denominator = 1;
+	int32_t fractional_len = 0;
+	int32_t exponent = 0;
+
+	errno = 0;
+	integral = g_ascii_strtoll(str, &endptr, 10);
+
+	if (errno)
+		return SR_ERR;
+
+	if (*endptr == '.') {
+		const char* start = endptr + 1;
+		fractional = g_ascii_strtoll(start, &endptr, 10);
+		if (errno)
+			return SR_ERR;
+		fractional_len = endptr - start;
+	}
+
+	if ((*endptr == 'E') || (*endptr == 'e')) {
+		exponent = g_ascii_strtoll(endptr + 1, &endptr, 10);
+		if (errno)
+			return SR_ERR;
+	}
+
+	if (*endptr != '\0')
+		return SR_ERR;
+
+	for (int i = 0; i < fractional_len; i++)
+		integral *= 10;
+	exponent -= fractional_len;
+
+	if (integral >= 0)
+		integral += fractional;
+	else
+		integral -= fractional;
+
+	while (exponent > 0) {
+		integral *= 10;
+		exponent--;
+	}
+
+	while (exponent < 0) {
+		denominator *= 10;
+		exponent++;
+	}
+
+	ret->p = integral;
+	ret->q = denominator;
+
+	return SR_OK;
+}
+
 /**
  * Convert a numeric value value to its "natural" string representation
  * in SI units.