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trezor-firmware/crypto/monero/serialize.c

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2018-07-05 00:10:34 +00:00
//
// Created by Dusan Klinec on 02/05/2018.
//
#include "serialize.h"
int xmr_size_varint(uint64_t num) {
int ctr = 1;
while (num >= 0x80) {
++ctr;
num >>= 7;
}
return ctr;
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}
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;
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}
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;
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}