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https://github.com/DrBeef/Raze.git
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114 lines
2.5 KiB
C
114 lines
2.5 KiB
C
#include "fix16.h"
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#include <stdbool.h>
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#include <ctype.h>
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static const uint32_t scales[8] = {
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/* 5 decimals is enough for full fix16_t precision */
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1, 10, 100, 1000, 10000, 100000, 100000, 100000
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};
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static char *itoa_loop(char *buf, uint32_t scale, uint32_t value, bool skip)
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{
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while (scale)
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{
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unsigned digit = (value / scale);
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if (!skip || digit || scale == 1)
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{
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skip = false;
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*buf++ = '0' + digit;
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value %= scale;
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}
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scale /= 10;
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}
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return buf;
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}
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void fix16_to_str(fix16_t value, char *buf, int decimals)
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{
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uint32_t uvalue = (value >= 0) ? value : -value;
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if (value < 0)
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*buf++ = '-';
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/* Separate the integer and decimal parts of the value */
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unsigned intpart = uvalue >> 16;
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uint32_t fracpart = uvalue & 0xFFFF;
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uint32_t scale = scales[decimals & 7];
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fracpart = fix16_mul(fracpart, scale);
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if (fracpart >= scale)
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{
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/* Handle carry from decimal part */
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intpart++;
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fracpart -= scale;
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}
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/* Format integer part */
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buf = itoa_loop(buf, 10000, intpart, true);
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/* Format decimal part (if any) */
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if (scale != 1)
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{
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*buf++ = '.';
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buf = itoa_loop(buf, scale / 10, fracpart, false);
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}
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*buf = '\0';
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}
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fix16_t fix16_from_str(const char *buf)
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{
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while (isspace(*buf))
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buf++;
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/* Decode the sign */
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bool negative = (*buf == '-');
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if (*buf == '+' || *buf == '-')
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buf++;
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/* Decode the integer part */
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uint32_t intpart = 0;
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int count = 0;
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while (isdigit(*buf))
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{
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intpart *= 10;
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intpart += *buf++ - '0';
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count++;
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}
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if (count == 0 || count > 5
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|| intpart > 32768 || (!negative && intpart > 32767))
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return fix16_overflow;
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fix16_t value = intpart << 16;
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/* Decode the decimal part */
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if (*buf == '.' || *buf == ',')
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{
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buf++;
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uint32_t fracpart = 0;
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uint32_t scale = 1;
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while (isdigit(*buf) && scale < 100000)
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{
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scale *= 10;
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fracpart *= 10;
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fracpart += *buf++ - '0';
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}
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value += fix16_div(fracpart, scale);
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}
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/* Verify that there is no garbage left over */
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while (*buf != '\0')
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{
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if (!isdigit(*buf) && !isspace(*buf))
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return fix16_overflow;
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buf++;
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}
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return negative ? -value : value;
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}
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