Fix read past end of array in sr_analog_si_prefix_friendly.

[libsigrok.git] / src / analog.c

diff --git a/src/analog.c b/src/analog.c
index a8ca3bce650424165227546b534924081dfbef3c..4eda290f1197f162f03e3e54b64330f1f1f3a5d0 100644 (file)
--- a/src/analog.c
+++ b/src/analog.c
@@ -119,6 +119,7 @@ static struct unit_mq_string mq_strings[] = {
        ALL_ZERO
 };
 
+/** @private */
 SR_PRIV int sr_analog_init(struct sr_datafeed_analog *analog,
                struct sr_analog_encoding *encoding,
                struct sr_analog_meaning *meaning,
@@ -173,8 +174,7 @@ SR_PRIV int sr_analog_init(struct sr_datafeed_analog *analog,
 SR_API int sr_analog_to_float(const struct sr_datafeed_analog *analog,
                float *outbuf)
 {
-       float offset;
-       unsigned int b, i, count;
+       unsigned int b, count;
        gboolean bigendian;
 
        if (!analog || !(analog->data) || !(analog->meaning)
@@ -274,7 +274,7 @@ SR_API int sr_analog_to_float(const struct sr_datafeed_analog *analog,
                /* The data is already in the right format. */
                memcpy(outbuf, analog->data, count * sizeof(float));
        } else {
-               for (i = 0; i < count; i += analog->encoding->unitsize) {
+               for (unsigned int i = 0; i < count; i += analog->encoding->unitsize) {
                        for (b = 0; b < analog->encoding->unitsize; b++) {
                                if (analog->encoding->is_bigendian == bigendian)
                                        ((uint8_t *)outbuf)[i + b] =
@@ -286,7 +286,7 @@ SR_API int sr_analog_to_float(const struct sr_datafeed_analog *analog,
                        if (analog->encoding->scale.p != 1
                                        || analog->encoding->scale.q != 1)
                                outbuf[i] = (outbuf[i] * analog->encoding->scale.p) / analog->encoding->scale.q;
-                       offset = ((float)analog->encoding->offset.p / (float)analog->encoding->offset.q);
+                       float offset = ((float)analog->encoding->offset.p / (float)analog->encoding->offset.q);
                        outbuf[i] += offset;
                }
        }
@@ -306,8 +306,10 @@ SR_API int sr_analog_to_float(const struct sr_datafeed_analog *analog,
  */
 SR_API const char *sr_analog_si_prefix(float *value, int *digits)
 {
-#define NEG_PREFIX_COUNT 5  /* number of prefixes below unity */
+/** @cond PRIVATE */
+#define NEG_PREFIX_COUNT 5 /* number of prefixes below unity */
 #define POS_PREFIX_COUNT (int)(ARRAY_SIZE(prefixes) - NEG_PREFIX_COUNT - 1)
+/** @endcond */
        static const char *prefixes[] = { "f", "p", "n", "µ", "m", "", "k", "M", "G", "T" };
 
        if (!value || !digits || isnan(*value))
@@ -329,6 +331,45 @@ SR_API const char *sr_analog_si_prefix(float *value, int *digits)
        return prefixes[prefix + NEG_PREFIX_COUNT];
 }
 
+/**
+ * Check if a unit "accepts" an SI prefix.
+ *
+ * E.g. SR_UNIT_VOLT is SI prefix friendly while SR_UNIT_DECIBEL_MW or
+ * SR_UNIT_PERCENTAGE are not.
+ *
+ * @param[in] unit The unit to check for SI prefix "friendliness".
+ *
+ * @return TRUE if the unit "accept" an SI prefix.
+ *
+ * @since 0.5.0
+ */
+SR_API gboolean sr_analog_si_prefix_friendly(enum sr_unit unit)
+{
+       static const enum sr_unit prefix_friendly_units[] = {
+               SR_UNIT_VOLT,
+               SR_UNIT_AMPERE,
+               SR_UNIT_OHM,
+               SR_UNIT_FARAD,
+               SR_UNIT_KELVIN,
+               SR_UNIT_HERTZ,
+               SR_UNIT_SECOND,
+               SR_UNIT_SIEMENS,
+               SR_UNIT_VOLT_AMPERE,
+               SR_UNIT_WATT,
+               SR_UNIT_WATT_HOUR,
+               SR_UNIT_METER_SECOND,
+               SR_UNIT_HENRY,
+               SR_UNIT_GRAM
+       };
+       unsigned int i;
+
+       for (i = 0; i < ARRAY_SIZE(prefix_friendly_units); i++)
+               if (unit == prefix_friendly_units[i])
+                       return TRUE;
+
+       return FALSE;
+}
+
 /**
  * Convert the unit/MQ/MQ flags in the analog struct to a string.
  *
@@ -510,8 +551,8 @@ SR_API int sr_rational_mult(struct sr_rational *res, const struct sr_rational *a
                return SR_ERR_ARG;
        }
 
-       res->p = (int64_t)(p);
-       res->q = (uint64_t)(q);
+       res->p = (int64_t)p;
+       res->q = (uint64_t)q;
 
        return SR_OK;