num_to_string.h

/*******************************************************************************
 *
 * Copyright (c) Simon Downey <[email protected]>
 *
 * The MIT License (MIT)
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
 * deal in the Software without restriction, including without limitation the
 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
 * sell copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 ******************************************************************************/

#ifndef NUM_TO_STRING_H
#define NUM_TO_STRING_H

#include <stdint.h>
#include <string.h>

const size_t MAX_NUM_TO_STRING_SIZE = 24;

static void NumToString(int64_t value, char* out) {
    if (out == NULL) {
        out[0] = '\0';
        return;
    }

    if (value == 0) {
        out[0] = '0';
        out[1] = '\0';
        return;
    }
  
    size_t    numDigits = 0UL;
    int64_t   base = 1LL;
    int64_t   tempInt = value;

    const size_t maxTmpSize = 24;

    if (value < 0) {
        out[0] = '-';
        tempInt = -tempInt;
    }

    while (base <= tempInt) {
        base *= 0x0A;
        numDigits++;
    }
  
    if (numDigits > maxTmpSize - 1) {
        out[0] = '\0';
        return;
    }

    base /= 0x0A;
    for (size_t i = 0; i < numDigits; i++) {
        out[i + (size_t)(value < 0)] = '0' + ((tempInt / base) % 0x0A);
        base /= 0x0A;
    }

    out[numDigits + (size_t)(value < 0)] = '\0';
}

static void NumToFloatString(int64_t amount, size_t decimals, char* out) {
    char temp[MAX_NUM_TO_STRING_SIZE];
  
    NumToString(amount, temp);

    size_t outLen = strlen(temp);

    if (decimals > outLen - (amount < 0) - 1 ||
        temp[0] == '0') {
        out[0] = '\0';
        return;
    }

    if (decimals > 0) {
        size_t offset = + outLen - decimals;

        strncpy(out, temp, offset);
        out[offset] = '.';
        strncpy(out + offset + 1,
                temp + offset,
                outLen - offset + 1);
    }
    else {
        strncpy(out, temp, outLen);
    }
}

#endif  //#define NUM_TO_STRING_HPP