53 lines
1.1 KiB
C++
53 lines
1.1 KiB
C++
//
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// Helper functions
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//
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char* dtostrf(double number, signed char width, unsigned char prec, char *s) {
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if(isnan(number)) {
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strcpy(s, "nan");
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return s;
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}
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if(isinf(number)) {
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strcpy(s, "inf");
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return s;
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}
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if(number > 4294967040.0 || number < -4294967040.0) {
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strcpy(s, "ovf");
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return s;
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}
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char* out = s;
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// Handle negative numbers
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if(number < 0.0) {
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*out = '-';
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++out;
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number = -number;
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}
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// Round correctly so that print(1.999, 2) prints as "2.00"
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double rounding = 0.5;
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for(uint8_t i = 0; i < prec; ++i)
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rounding /= 10.0;
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number += rounding;
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// Extract the integer part of the number and print it
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unsigned long int_part = (unsigned long) number;
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double remainder = number - (double) int_part;
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out += sprintf(out, "%d", int_part);
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// Print the decimal point, but only if there are digits beyond
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if(prec > 0) {
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*out = '.';
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++out;
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}
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while(prec-- > 0) {
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remainder *= 10.0;
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}
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sprintf(out, "%d", (int) remainder);
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return s;
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}
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