brymen-bm25x: properly set encoding digits

diff --git a/src/dmm/bm25x.c b/src/dmm/bm25x.c
index d7468f49bfd300a5dd303da470bdad42810bec64..4966eedb0742ff4f00b4534b7c96627cf4605883 100644 (file)
--- a/src/dmm/bm25x.c
+++ b/src/dmm/bm25x.c
@@ -94,36 +94,31 @@ static int decode_point(const uint8_t *buf)
        return p;
 }
 
-static float scale_value(float val, int point, int digits)
+static int decode_scale(int point, int digits)
 {
        int pos;
 
        pos = point ? point + digits - MAX_DIGITS : 0;
 
-       switch (pos) {
-       case 0: return val;
-       case 1: return val * 1e-1;
-       case 2: return val * 1e-2;
-       case 3: return val * 1e-3;
+       if (pos < 0 || pos > 3) {
+               sr_dbg("Invalid decimal point %d (%d digits).", point, digits);
+               return 0;
        }
-
-       sr_dbg("Invalid decimal point %d (%d digits).", point, digits);
-
-       return NAN;
+       return -pos;
 }
 
-static float decode_prefix(const uint8_t *buf)
+static int decode_prefix(const uint8_t *buf)
 {
-       if (buf[11] & 2) return 1e+6;
-       if (buf[11] & 1) return 1e+3;
-       if (buf[13] & 1) return 1e-3;
-       if (buf[13] & 2) return 1e-6;
-       if (buf[12] & 1) return 1e-9;
+       if (buf[11] & 2) return  6;
+       if (buf[11] & 1) return  3;
+       if (buf[13] & 1) return -3;
+       if (buf[13] & 2) return -6;
+       if (buf[12] & 1) return -9;
 
-       return 1.0f;
+       return 0;
 }
 
-static float decode_value(const uint8_t *buf)
+static float decode_value(const uint8_t *buf, int *exponent)
 {
        float val = 0.0f;
        int i, digit;
@@ -137,7 +132,8 @@ static float decode_value(const uint8_t *buf)
                val = 10.0 * val + digit;
        }
 
-       return scale_value(val, decode_point(buf), i);
+       *exponent = decode_scale(decode_point(buf), i);
+       return val;
 
 special:
        if (decode_digit(1, buf) == 0 && decode_digit(2, buf) == 'L')
@@ -149,6 +145,7 @@ special:
 SR_PRIV int sr_brymen_bm25x_parse(const uint8_t *buf, float *floatval,
                                struct sr_datafeed_analog *analog, void *info)
 {
+       int exponent = 0;
        float val;
 
        (void)info;
@@ -204,12 +201,16 @@ SR_PRIV int sr_brymen_bm25x_parse(const uint8_t *buf, float *floatval,
                analog->meaning->unit = SR_UNIT_FAHRENHEIT;
        }
 
-       val = decode_value(buf) * decode_prefix(buf);
+       val = decode_value(buf, &exponent);
+       exponent += decode_prefix(buf);
+       val *= powf(10, exponent);
 
        if (buf[3] & 1)
                val = -val;
 
        *floatval = val;
+       analog->encoding->digits  = -exponent;
+       analog->spec->spec_digits = -exponent;
 
        return SR_OK;
 }