From 075b620a86b6a03af56f0cf2a694e843edd392b2 Mon Sep 17 00:00:00 2001
From: dwarning <dwarning>
Date: Tue, 20 Aug 2013 21:39:20 +0200
Subject: [PATCH] introduce `cx_sortorder()' function

---
 src/frontend/parse.c         |  1 +
 src/include/ngspice/fteext.h |  1 +
 src/maths/cmaths/cmath1.c    | 58 ++++++++++++++++++++++++++++++++++++
 src/maths/cmaths/cmath1.h    |  1 +
 4 files changed, 61 insertions(+)

diff --git a/src/frontend/parse.c b/src/frontend/parse.c
index 29457a1de..ad3b7f1a5 100644
--- a/src/frontend/parse.c
+++ b/src/frontend/parse.c
@@ -162,6 +162,7 @@ struct func ft_funcs[] = {
     { "cosh",        cx_cosh },
     { "tanh",        cx_tanh },
     { "atan",        cx_atan },
+    { "sortorder",   cx_sortorder },
     { "norm",        cx_norm },
     { "rnd",         cx_rnd },
     { "sunif",       cx_sunif },
diff --git a/src/include/ngspice/fteext.h b/src/include/ngspice/fteext.h
index 9c70d15a4..5e98cfc5c 100644
--- a/src/include/ngspice/fteext.h
+++ b/src/include/ngspice/fteext.h
@@ -74,6 +74,7 @@ extern void *cx_tanh(void *, short int , int , int *, short int *);
 extern void *cx_atan(void *, short int , int , int *, short int *);
 extern void *cx_floor(void *, short int , int , int *, short int *);
 extern void *cx_ceil(void *, short int , int , int *, short int *);
+extern void *cx_sortorder(void *, short int , int , int *, short int *);
 
 /* cmath2.c */
 
diff --git a/src/maths/cmaths/cmath1.c b/src/maths/cmaths/cmath1.c
index b8427ec22..d96e16cb0 100644
--- a/src/maths/cmaths/cmath1.c
+++ b/src/maths/cmaths/cmath1.c
@@ -709,3 +709,61 @@ cx_atan(void *data, short int type, int length, int *newlength, short int *newty
     }
     return ((void *) d);
 }
+
+/* Struct to store and order the values of the amplitudes preserving the index in the original array */
+typedef struct {
+    double amplitude;
+    int index;
+} amplitude_index_t;
+
+static int compare_structs (const void *a, const void *b);
+
+/*
+ *  Returns the positions of the elements in a real vector
+ *  after they have been sorted into increasing order using a stable method (qsort).
+ */
+
+void *
+cx_sortorder(void *data, short int type, int length, int *newlength, short int *newtype)
+{
+    double *d = alloc_d(length);
+    double *dd = (double *) data;
+    int i;
+
+    amplitude_index_t *array_amplitudes;
+    array_amplitudes = (amplitude_index_t *) malloc(sizeof(amplitude_index_t) * (size_t) length);
+
+    *newlength = length;
+    *newtype = VF_REAL;
+    if (type == VF_REAL) {
+
+        for(i = 0; i < length; i++){
+            array_amplitudes[i].amplitude = dd[i];
+            array_amplitudes[i].index = i;
+        }
+
+        qsort(array_amplitudes, (size_t) length, sizeof(array_amplitudes[0]), compare_structs);
+
+        for(i = 0; i < length; i++)
+            d[i] = array_amplitudes[i].index;
+    }
+
+    free(array_amplitudes);
+
+    /* Otherwise it is 0, but tmalloc zeros the stuff already. */
+    return ((void *) d);
+}
+
+static int
+compare_structs(const void *a, const void *b)
+{
+    amplitude_index_t *aa = (amplitude_index_t *) a;
+    amplitude_index_t *bb = (amplitude_index_t *) b;
+
+    if (aa->amplitude > bb->amplitude)
+        return 1;
+    else if (aa->amplitude == bb->amplitude)
+        return 0;
+    else
+        return -1;
+}
diff --git a/src/maths/cmaths/cmath1.h b/src/maths/cmaths/cmath1.h
index 165738a9a..b6456f3d7 100644
--- a/src/maths/cmaths/cmath1.h
+++ b/src/maths/cmaths/cmath1.h
@@ -27,6 +27,7 @@ void * cx_cosh(void *data, short int type, int length, int *newlength, short int
 void * cx_tan(void *data, short int type, int length, int *newlength, short int *newtype);
 void * cx_tanh(void *data, short int type, int length, int *newlength, short int *newtype);
 void * cx_atan(void *data, short int type, int length, int *newlength, short int *newtype);
+void * cx_sortorder(void *data, short int type, int length, int *newlength, short int *newtype);
 
 
 #endif