From 533d39b4c2c3bb29e032da99a0d73ceaf6d20fc6 Mon Sep 17 00:00:00 2001
From: Muhammet Asan <ext-muhammet.asan@here.com>
Date: Thu, 14 Feb 2019 13:25:34 +0100
Subject: [PATCH] 10 times faster int to string implementation

---
 lv_misc/lv_math.c | 64 ++++++++++++++++-------------------------------
 1 file changed, 22 insertions(+), 42 deletions(-)

diff --git a/lv_misc/lv_math.c b/lv_misc/lv_math.c
index a0d26053e..394246916 100644
--- a/lv_misc/lv_math.c
+++ b/lv_misc/lv_math.c
@@ -34,7 +34,7 @@ static int16_t sin0_90_table[] = {
     28377, 28659,  28932,  29196,  29451,  29697,  29934,  30162,  30381,  30591,
     30791, 30982,  31163,  31335,  31498,  31650,  31794,  31927,  32051,  32165,
     32269, 32364,  32448,  32523,  32587,  32642,  32687,  32722,  32747,  32762,
-	32767
+    32767
 };
 
 
@@ -54,53 +54,33 @@ static int16_t sin0_90_table[] = {
  */
 char * lv_math_num_to_str(int32_t num, char * buf)
 {
-    char * buf_ori = buf;
-    if(num == 0) {
+    if (num == 0) {
         buf[0] = '0';
         buf[1] = '\0';
         return buf;
-    } else if(num < 0) {
-        (*buf) = '-';
-        buf++;
-        num = LV_MATH_ABS(num);
     }
-    uint32_t output = 0;
-    int8_t i;
-
-    for(i = 31; i >= 0; i--) {
-        if((output & 0xF) >= 5)
-            output += 3;
-        if(((output & 0xF0) >> 4) >= 5)
-            output += (3 << 4);
-        if(((output & 0xF00) >> 8) >= 5)
-            output += (3 << 8);
-        if(((output & 0xF000) >> 12) >= 5)
-            output += (3 << 12);
-        if(((output & 0xF0000) >> 16) >= 5)
-            output += (3 << 16);
-        if(((output & 0xF00000) >> 20) >= 5)
-            output += (3 << 20);
-        if(((output & 0xF000000) >> 24) >= 5)
-            output += (3 << 24);
-        if(((output & 0xF0000000) >> 28) >= 5)
-            output += (3 << 28);
-        output = (output << 1) | ((num >> i) & 1);
+    int8_t digitCount = 0;
+    int8_t i = 0;
+    if (num < 0) {
+        buf[digitCount++] = '-';
+        num = abs(num);
+        ++i;
     }
-
-    uint8_t digit;
-    bool leading_zero_ready = false;
-    for(i = 28; i >= 0; i -= 4) {
-        digit = ((output >> i) & 0xF) + '0';
-        if(digit == '0' && leading_zero_ready == false) continue;
-
-        leading_zero_ready = true;
-        (*buf) = digit;
-        buf++;
+    while (num) {
+        char digit = num % 10;
+        buf[digitCount++] = digit + 48;
+        num /= 10;
     }
-
-    (*buf) = '\0';
-
-    return buf_ori;
+    buf[digitCount] = '\0';
+    digitCount--;
+    while (digitCount > i) {
+        char temp = buf[i];
+        buf[i] = buf[digitCount];
+        buf[digitCount] = temp;
+        digitCount--;
+        i++;
+    }
+    return buf;
 }
 
 /**