From c1d08e30444ee58596f91b6f2968a7e521c08dc2 Mon Sep 17 00:00:00 2001
From: Frederik Beimgraben <frederik@beimgraben.net>
Date: Fri, 17 Jan 2025 20:24:35 +0100
Subject: [PATCH] Refactor any copying of arrays for performance using memcpy

---
 MMS24-25.c | 45 ++++++++++++++++++++-------------------------
 Makefile   |  2 +-
 2 files changed, 21 insertions(+), 26 deletions(-)

diff --git a/MMS24-25.c b/MMS24-25.c
index 26a74e6..72ece9d 100644
--- a/MMS24-25.c
+++ b/MMS24-25.c
@@ -15,6 +15,7 @@
 #include <stdio.h>
 #include <math.h>
 #include <stdlib.h>
+#include <string.h>
 #include <stdarg.h>   // For variadic functions
 
 // UNIX Libraries
@@ -118,6 +119,20 @@ void _warn(char *fmt, ...) {
 }
 // #endregion
 
+/*
+ * Copies an array of doubles *fast*.
+ */
+void _copy_double_array(double *dst, double *src, int len) {
+    memcpy(dst, src, len * sizeof(double));
+}
+
+/*
+ * Copies an array of integers *fast*.
+ */
+void _copy_int_array(int *dst, int *src, int len) {
+    memcpy(dst, src, len * sizeof(int));
+}
+
 // #region C99 Compatibility
 #if _GNU_SOURCE || _POSIX_C_SOURCE >= 200809L || _XOPEN_SOURCE >= 700
 #else
@@ -439,9 +454,7 @@ LocalExtrema* copyLocalExtrema(LocalExtrema *pexIn) {
     if (localExtrema->piLocalExtremaPos == NULL)
         _mem_error("copyLocalExtrema: Failed to allocate memory for localExtrema->piLocalExtremaPos");
 
-    for (int i = 0; i < pexIn->iNumLocalExtrema; i++) {
-        localExtrema->piLocalExtremaPos[i] = pexIn->piLocalExtremaPos[i];
-    }
+    _copy_int_array(localExtrema->piLocalExtremaPos, pexIn->piLocalExtremaPos, pexIn->iNumLocalExtrema);
 
     return localExtrema;
 }
@@ -478,9 +491,7 @@ MMSignal *createSignalFromSignal(MMSignal *pmmsIn) {
         if (signal->pdValues == NULL)
             _mem_error("createSignalFromSignal: Failed to allocate memory for signal->pdValues");
 
-        for (int i = 0; i < pmmsIn->iNumValues; i++) {
-            signal->pdValues[i] = pmmsIn->pdValues[i];
-        }
+        _copy_double_array(signal->pdValues, pmmsIn->pdValues, pmmsIn->iNumValues);
     } else {
         if (pmmsIn->iNumValues != 0)
             _error("createSignalFromSignal: pmmsIn->pdValues is NULL while pmmsIn->iNumValues is not %d", pmmsIn->iNumValues);
@@ -539,9 +550,7 @@ MMSignal *createSignalFromDoubleArray(int iArrayLen, double *pdIn) {
     if (signal->pdValues == NULL)
         _mem_error("createSignalFromDoubleArray: Failed to allocate memory for signal->pdValues");
 
-    for (int i = 0; i < iArrayLen; i++) {
-        signal->pdValues[i] = pdIn[i];
-    }
+    _copy_double_array(signal->pdValues, pdIn, iArrayLen);
 
     signal->iNumValues = iArrayLen;
 
@@ -720,14 +729,12 @@ double calculateMedian(double *pdIn, int iLen) {
     }
 
     double *pdInSorted = NULL;
-    pdInSorted = (double*) malloc(sizeof(double) *iLen);
+    pdInSorted = (double*) malloc(sizeof(double) * iLen);
 
     if (pdInSorted == NULL)
         _mem_error("calculateMedian: Failed to allocate memory for pdInSorted");
 
-    for (int i = 0; i < iLen; i++) {
-        pdInSorted[i] = pdIn[i];
-    }
+    _copy_double_array(pdInSorted, pdIn, iLen);
 
     // Sort the array using stdlib's qsort function
     qsort(pdInSorted, iLen, sizeof(double), compareDoubles);
@@ -900,18 +907,6 @@ Histogram *initHistogram(double *pdIn, int iLen, int iNumBins) {
     if (iNumBins == 0)
         _error("initHistogram: iNumBins must be non-0");
 
-    /*if (iLen == 0) // FIXME: This should be an error in the final version
-        _error("initHistogram: iLen is 0");
-
-    histogram->dIntervalMin = pdIn[0];
-    histogram->dIntervalMax = pdIn[0];
-    for (int i = 0; i < iLen; i++) {
-        if (pdIn[i] < histogram->dIntervalMin)
-            histogram->dIntervalMin = pdIn[i];
-        if (pdIn[i] > histogram->dIntervalMax)
-            histogram->dIntervalMax = pdIn[i];
-    }*/
-
     int minPos, maxPos;
     getMinMaxPos(pdIn, iLen, &minPos, &maxPos);
     histogram->dIntervalMin = pdIn[minPos];
diff --git a/Makefile b/Makefile
index f1301eb..600c731 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,6 @@
 CC=gcc
 SOURCE_FILE=MMS24-25.c
-OPTS=-lm -D _DEBUG
+OPTS=-lm -D _DEBUG -std=c99
 
 all: clean tests run