Momentum-Firmware/applications/external/flipbip/lib/crypto/monero/serialize.c

//
// Created by Dusan Klinec on 02/05/2018.
//

#if USE_MONERO

#include "serialize.h"

int xmr_size_varint(uint64_t num) {
    int ctr = 1;
    while(num >= 0x80) {
        ++ctr;
        num >>= 7;
    }
    return ctr;
}

int xmr_write_varint(uint8_t* buff, size_t buff_size, uint64_t num) {
    unsigned ctr = 0;
    while(num >= 0x80 && ctr < buff_size) {
        *buff = (uint8_t)(((num)&0x7f) | 0x80);
        ++buff;
        ++ctr;
        num >>= 7;
    }

    /* writes the last one to dest */
    if(ctr < buff_size) {
        *buff = (uint8_t)num;
        ++ctr;
    }
    return ctr <= buff_size ? (int)ctr : -1;
}

int xmr_read_varint(uint8_t* buff, size_t buff_size, uint64_t* val) {
    unsigned read = 0;
    int finished_ok = 0;
    *val = 0;

    for(int shift = 0; read < buff_size; shift += 7, ++read) {
        uint8_t byte = buff[read];
        if((byte == 0 && shift != 0) || (shift >= 63 && byte > 1)) {
            return -1;
        }

        *val |= (uint64_t)(byte & 0x7f) << shift;

        /* If there is no next */
        if((byte & 0x80) == 0) {
            finished_ok = 1;
            break;
        }
    }
    return finished_ok ? (int)read + 1 : -2;
}

#endif // USE_MONERO