From eb376899ce429b6f4deac6260076fb82b4ee1520 Mon Sep 17 00:00:00 2001
From: Gabor Kiss-Vamosi <kisvegabor@gmail.com>
Date: Sun, 4 Mar 2018 17:51:41 +0100
Subject: [PATCH] remove sprintf from lv_gauge the save ROM (custom BCD
 converter added to lv_math.c)

---
 lv_misc/lv_math.c  | 96 ++++++++++++++++++++++++++++++++++++++++++++++
 lv_misc/lv_math.h  |  2 +
 lv_objx/lv_gauge.c |  3 +-
 3 files changed, 100 insertions(+), 1 deletion(-)
 create mode 100644 lv_misc/lv_math.c

diff --git a/lv_misc/lv_math.c b/lv_misc/lv_math.c
new file mode 100644
index 000000000..128b32c9c
--- /dev/null
+++ b/lv_misc/lv_math.c
@@ -0,0 +1,96 @@
+/**
+ * @file lv_math.c
+ *
+ */
+
+/*********************
+ *      INCLUDES
+ *********************/
+#include "lv_math.h"
+#include <stdbool.h>
+
+/*********************
+ *      DEFINES
+ *********************/
+
+/**********************
+ *      TYPEDEFS
+ **********************/
+
+/**********************
+ *  STATIC PROTOTYPES
+ **********************/
+
+/**********************
+ *  STATIC VARIABLES
+ **********************/
+
+/**********************
+ *      MACROS
+ **********************/
+
+/**********************
+ *   GLOBAL FUNCTIONS
+ **********************/
+
+/**
+ * Convert a number to string
+ * @param num a number
+ * @param buf pointer to a `char` buffer. The result will be stored here (max 10 elements)
+ */
+void lv_math_num_to_str(int32_t num, char * buf)
+{
+    char * buf_ori = buf;
+    if(num == 0) {
+        buf[0] = '0';
+        buf[1] = '\0';
+        return;
+    } 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);
+    }
+
+    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++;
+    }
+
+    (*buf) = '\0';
+
+    printf("Input decimal or binary: %d\nOutput BCD: %X\nOutput str: %s\n", num, output, buf_ori);
+}
+
+/**********************
+ *   STATIC FUNCTIONS
+ **********************/
+
+
diff --git a/lv_misc/lv_math.h b/lv_misc/lv_math.h
index d537f7de8..458f26d38 100644
--- a/lv_misc/lv_math.h
+++ b/lv_misc/lv_math.h
@@ -14,6 +14,7 @@ extern "C" {
 /*********************
  *      INCLUDES
  *********************/
+#include <stdint.h>
 
 /*********************
  *      DEFINES
@@ -30,6 +31,7 @@ extern "C" {
 /**********************
  * GLOBAL PROTOTYPES
  **********************/
+void lv_math_num_to_str(int32_t num, char * buf);
 
 /**********************
  *      MACROS
diff --git a/lv_objx/lv_gauge.c b/lv_objx/lv_gauge.c
index 03f9519d7..e5468b243 100644
--- a/lv_objx/lv_gauge.c
+++ b/lv_objx/lv_gauge.c
@@ -353,7 +353,8 @@ static void lv_gauge_draw_scale(lv_obj_t * gauge, const lv_area_t * mask)
 
         int16_t scale_act = (int32_t)((int32_t)(max - min) * i) /  (label_num - 1);
         scale_act += min;
-        sprintf(scale_txt, "%d", scale_act);
+        lv_math_num_to_str(scale_act, scale_txt);
+//        sprintf(scale_txt, "%d", scale_act);
 
         lv_area_t label_cord;
         lv_point_t label_size;