From 1ba85b048b5d7e9cee0453b48a1f0ff16990cfa7 Mon Sep 17 00:00:00 2001
From: Jamie Bullock <jamie@jamiebullock.com>
Date: Tue, 11 Feb 2014 16:39:41 +0000
Subject: Make xtract_lowest_value() return XTRACT_NO_RESULT if all values in
 the input data are below or equal to threshold value. Fixes #46

If XTRACT_NO_RESULT is returned, *result will be set to DBL_MAX
---
 examples/simpletest/simpletest.c | 15 +++++++++++++++
 src/scalar.c                     |  9 ++++++---
 xtract/xtract_scalar.h           |  7 ++++++-
 3 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/examples/simpletest/simpletest.c b/examples/simpletest/simpletest.c
index 14fd6ee..443de22 100644
--- a/examples/simpletest/simpletest.c
+++ b/examples/simpletest/simpletest.c
@@ -98,6 +98,7 @@ int main(void)
     double f0 = 0.0;
     double flux = 0.0;
     double centroid = 0.0;
+    double lowest = 0.0;
     double spectrum[BLOCKSIZE] = {0};
     double windowed[BLOCKSIZE] = {0};
     double peaks[BLOCKSIZE] = {0};
@@ -109,6 +110,7 @@ int main(void)
     double argd[4] = {0};
     double samplerate = 44100.0;
     int n;
+    int rv = XTRACT_SUCCESS;
     xtract_mel_filter mel_filters;
 
     fill_wavetable(344.53125f, NOISE); // 344.53125f = 128 samples @ 44100 Hz
@@ -122,6 +124,19 @@ int main(void)
     xtract[XTRACT_MEAN](wavetable, BLOCKSIZE, NULL, &mean);
     printf("\nInput mean = %.2f\n\n", mean); /* We expect this to be zero for a square wave */  
 
+    /* get the lowest value in the input */
+    argd[0] = -.5;
+    rv = xtract[XTRACT_LOWEST_VALUE](wavetable, BLOCKSIZE, argd, &lowest);
+    
+    if (rv == XTRACT_SUCCESS)
+    {
+        printf("\nLowest value = %.6f\n\n", lowest);
+    }
+    else
+    {
+        printf("\nUnable to get lowest value, all values below threshold?\n\n");
+    }
+    exit(0);    
     /* create the window function */
     window = xtract_init_window(BLOCKSIZE, XTRACT_HANN);
     xtract_windowed(wavetable, BLOCKSIZE, window, windowed);
diff --git a/src/scalar.c b/src/scalar.c
index 934f14e..3ecd446 100644
--- a/src/scalar.c
+++ b/src/scalar.c
@@ -27,6 +27,7 @@
 #include <string.h>
 #include <stdio.h>
 #include <math.h>
+#include <limits.h>
 
 #include "dywapitchtrack/dywapitchtrack.h"
 
@@ -746,16 +747,18 @@ int xtract_lowest_value(const double *data, const int N, const void *argv, doubl
 {
 
     int n = N;
-    double temp;
 
-    *result = data[--n];
+    *result = DBL_MAX;
 
     while(n--)
     {
-        if((temp = data[n]) > *(double *)argv)
+        if(data[n] > *(double *)argv)
             *result = XTRACT_MIN(*result, data[n]);
     }
 
+    if (*result == DBL_MAX)
+        return XTRACT_NO_RESULT;
+        
     return XTRACT_SUCCESS;
 }
 
diff --git a/xtract/xtract_scalar.h b/xtract/xtract_scalar.h
index 50fc213..dc0e5cf 100644
--- a/xtract/xtract_scalar.h
+++ b/xtract/xtract_scalar.h
@@ -353,8 +353,13 @@ int xtract_spectral_slope(const double *data, const int N, const void *argv, dou
  * 
  * \param *data: a pointer to the first element in an array of doubles
  * \param N: the number of elements to be considered
- * \param *argv: a pointer to a double representing the lower limit for the search. i.e. (*result > *argv) returns 1.
+ * \param *argv: a pointer to a double representing the lower limit for the search. All values in the array pointed to by *data that are below or equal to this threshold will be ignored.
  * \param *result: a pointer to a value representing the lowest component in *data that falls above a given threshold. 
+ *
+ * \return XTRACT_SUCCESS is a lowest value was found or XTRACT_NO_VALUE if all values 
+ * in the array pointed to by *data are below or equal to the threshold set with *argv
+ *
+ * \note If XTRACT_NO_VALUE is returned, *result will be set to DBL_MAX
  * 
  */
 int xtract_lowest_value(const double *data, const int N, const void *argv, double *result);
-- 
cgit v1.2.3