scpi-pps: Support for the EEZ PSU series

[libsigrok.git] / src / strutil.c

diff --git a/src/strutil.c b/src/strutil.c
index 0dff3c4b48c0bf8df4014f73bddde9dd279644c3..c22c71757f30e42aa08b9e567eb11eeb9a802850 100644 (file)
--- a/src/strutil.c
+++ b/src/strutil.c
@@ -145,6 +145,60 @@ SR_PRIV int sr_atol_base(const char *str, long *ret, char **end, int base)
        return SR_OK;
 }
 
+/**
+ * Convert a text to a number including support for non-decimal bases.
+ * Also optionally returns the position after the number, where callers
+ * can either error out, or support application specific suffixes.
+ *
+ * @param[in] str The input text to convert.
+ * @param[out] ret The conversion result.
+ * @param[out] end The position after the number.
+ * @param[in] base The number format's base, can be 0.
+ *
+ * @retval SR_OK Conversion successful.
+ * @retval SR_ERR Conversion failed.
+ *
+ * @private
+ *
+ * This routine is more general than @ref sr_atol(), which strictly
+ * expects the input text to contain just a decimal number, and nothing
+ * else in addition. The @ref sr_atoul_base() routine accepts trailing
+ * text after the number, and supports non-decimal numbers (bin, hex),
+ * including automatic detection from prefix text.
+ */
+SR_PRIV int sr_atoul_base(const char *str, unsigned long *ret, char **end, int base)
+{
+       unsigned long num;
+       char *endptr;
+
+       /* Add "0b" prefix support which strtol(3) may be missing. */
+       while (str && isspace(*str))
+               str++;
+       if (!base && strncmp(str, "0b", strlen("0b")) == 0) {
+               str += strlen("0b");
+               base = 2;
+       }
+
+       /* Run the number conversion. Quick bail out if that fails. */
+       errno = 0;
+       endptr = NULL;
+       num = strtoul(str, &endptr, base);
+       if (!endptr || errno) {
+               if (!errno)
+                       errno = EINVAL;
+               return SR_ERR;
+       }
+       *ret = num;
+
+       /* Advance to optional non-space trailing suffix. */
+       while (endptr && isspace(*endptr))
+               endptr++;
+       if (end)
+               *end = endptr;
+
+       return SR_OK;
+}
+
 /**
  * Convert a string representation of a numeric value (base 10) to an integer. The
  * conversion is strict and will fail if the complete string does not represent
@@ -272,6 +326,77 @@ SR_PRIV int sr_atod_ascii(const char *str, double *ret)
        return SR_OK;
 }
 
+/**
+ * Convert text to a floating point value, and get its precision.
+ *
+ * @param[in] str The input text to convert.
+ * @param[out] ret The conversion result, a double precision float number.
+ * @param[out] digits The number of significant decimals.
+ *
+ * @returns SR_OK in case of successful text to number conversion.
+ * @returns SR_ERR when conversion fails.
+ *
+ * @since 0.6.0
+ */
+SR_PRIV int sr_atod_ascii_digits(const char *str, double *ret, int *digits)
+{
+       const char *p;
+       int *dig_ref, m_dig, exp;
+       char c;
+       double f;
+
+       /*
+        * Convert floating point text to the number value, _and_ get
+        * the value's precision in the process. Steps taken to do it:
+        * - Skip leading whitespace.
+        * - Count the number of decimals after the mantissa's period.
+        * - Get the exponent's signed value.
+        *
+        * This implementation still uses common code for the actual
+        * conversion, but "violates API layers" by duplicating the
+        * text scan, to get the number of significant digits.
+        */
+       p = str;
+       while (*p && isspace(*p))
+               p++;
+       if (*p == '-' || *p == '+')
+               p++;
+       m_dig = 0;
+       exp = 0;
+       dig_ref = NULL;
+       while (*p) {
+               c = *p++;
+               if (toupper(c) == 'E') {
+                       exp = strtol(p, NULL, 10);
+                       break;
+               }
+               if (c == '.') {
+                       m_dig = 0;
+                       dig_ref = &m_dig;
+                       continue;
+               }
+               if (isdigit(c)) {
+                       if (dig_ref)
+                               (*dig_ref)++;
+                       continue;
+               }
+               /* Need not warn, conversion will fail. */
+               break;
+       }
+       sr_spew("atod digits: txt \"%s\" -> m %d, e %d -> digits %d",
+               str, m_dig, exp, m_dig + -exp);
+       m_dig += -exp;
+
+       if (sr_atod_ascii(str, &f) != SR_OK)
+               return SR_ERR;
+       if (ret)
+               *ret = f;
+       if (digits)
+               *digits = m_dig;
+
+       return SR_OK;
+}
+
 /**
  * Convert a string representation of a numeric value to a float. The
  * conversion is strict and will fail if the complete string does not represent