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Merge pull request #841 from muhammetasan/master

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10 times faster int to string implementation
This commit is contained in:
Gabor Kiss-Vamosi 2019-02-15 15:09:53 +01:00 committed by GitHub
commit 2af6ca8833
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GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 22 additions and 42 deletions
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62
lv_misc/lv_math.c
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@ -54,53 +54,33 @@ static int16_t sin0_90_table[] = {
*/ */
char * lv_math_num_to_str(int32_t num, char * buf) 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[0] = '0';
buf[1] = '\0'; buf[1] = '\0';
return buf; return buf;
} else if(num < 0) {
(*buf) = '-';
buf++;
num = LV_MATH_ABS(num);
} }
uint32_t output = 0; int8_t digitCount = 0;
int8_t i; int8_t i = 0;
if (num < 0) {
for(i = 31; i >= 0; i--) { buf[digitCount++] = '-';
if((output & 0xF) >= 5) num = abs(num);
output += 3; ++i;
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);
} }
while (num) {
uint8_t digit; char digit = num % 10;
bool leading_zero_ready = false; buf[digitCount++] = digit + 48;
for(i = 28; i >= 0; i -= 4) { num /= 10;
digit = ((output >> i) & 0xF) + '0';
if(digit == '0' && leading_zero_ready == false) continue;
leading_zero_ready = true;
(*buf) = digit;
buf++;
} }
buf[digitCount] = '\0';
(*buf) = '\0'; digitCount--;
while (digitCount > i) {
return buf_ori; char temp = buf[i];
buf[i] = buf[digitCount];
buf[digitCount] = temp;
digitCount--;
i++;
}
return buf;
} }
/** /**