From 63fcc1165b378e63debbc1f769661bb362ff3533 Mon Sep 17 00:00:00 2001
From: JackieWu <wkcn@live.cn>
Date: Tue, 1 Sep 2020 00:27:00 +0800
Subject: [PATCH] =?UTF-8?q?=E5=8E=BB=E6=8E=89imread=E5=87=BD=E6=95=B0?=
 =?UTF-8?q?=E4=B8=AD=E5=A4=9A=E4=BD=99=E7=9A=84=E6=95=B0=E6=8D=AE=E6=8B=B7?=
 =?UTF-8?q?=E8=B4=9D=20(#392)?=
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* remove unnecessary copy

* combine loop
---
 examples/common/tengine_operations.c | 46 ++++++----------------------
 1 file changed, 10 insertions(+), 36 deletions(-)

diff --git a/examples/common/tengine_operations.c b/examples/common/tengine_operations.c
index 52386ea0..f29d25fd 100644
--- a/examples/common/tengine_operations.c
+++ b/examples/common/tengine_operations.c
@@ -634,41 +634,23 @@ void combination_image(image source, image dest, int dx, int dy)
 
 image imread(const char* filename)
 {
-    image im = load_image_stb(filename, 0);
-    for (int c = 0; c < im.c; c++)
-    {
-        for (int h = 0; h < im.h; h++)
-        {
-            for (int w = 0; w < im.w; w++)
-            {
-                int newIndex = ( c )*im.h * im.w + h * im.w + w;
-                im.data[newIndex] = im.data[newIndex];
-            }
-        }
-    }
-    return im;
+    return load_image_stb(filename, 0);
 }
 
 image imread2post(const char* filename)
 {
     image im = load_image_stb(filename, 0);
-    for (int c = 0; c < im.c; c++)
-    {
-        for (int h = 0; h < im.h; h++)
-        {
-            for (int w = 0; w < im.w; w++)
-            {
-                int newIndex = ( c )*im.h * im.w + h * im.w + w;
-                im.data[newIndex] = im.data[newIndex] * 255;
-            }
-        }
+    const int len = im.c * im.h * im.w;
+    for (int i = 0; i < len; ++i) {
+        im.data[i] *= 255;
     }
     return im;
 }
 
 image rgb2bgr_premute(image src)
 {
-    float* GRB = ( float* )malloc(sizeof(float) * src.c * src.h * src.w);
+    const int len = src.c * src.h * src.w;
+    float* GRB = ( float* )malloc(sizeof(float) * len);
     for (int c = 0; c < src.c; c++)
     {
         for (int h = 0; h < src.h; h++)
@@ -681,16 +663,8 @@ image rgb2bgr_premute(image src)
             }
         }
     }
-    for (int c = 0; c < src.c; c++)
-    {
-        for (int h = 0; h < src.h; h++)
-        {
-            for (int w = 0; w < src.w; w++)
-            {
-                int newIndex = ( c )*src.h * src.w + h * src.w + w;
-                src.data[newIndex] = GRB[newIndex];
-            }
-        }
+    for (int i = 0; i < len; ++i) {
+        src.data[i] = GRB[i];
     }
     free(GRB);
     return src;
@@ -808,7 +782,7 @@ void draw_circle(image im, int x, int y, int radius, int r, int g, int b)
 
 void subtract(image a, image b, image c)
 {
-    int size = a.c * a.h * a.w;
+    const int size = a.c * a.h * a.w;
     for (int i = 0; i < size; i++)
     {
         c.data[i] = a.data[i] - b.data[i];
@@ -820,7 +794,7 @@ void subtract(image a, image b, image c)
 
 void multi(image a, float value, image b)
 {
-    int size = a.c * a.h * a.w;
+    const int size = a.c * a.h * a.w;
     for (int i = 0; i < size; i++)
     {
         b.data[i] = a.data[i] * value;
-- 
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