root/varint.c

DEFINITIONS

1. decode_varint
2. encode_varint

#include "git-compat-util.h"
#include "varint.h"

uintmax_t decode_varint(const unsigned char **bufp)
{
        const unsigned char *buf = *bufp;
        unsigned char c = *buf++;
        uintmax_t val = c & 127;
        while (c & 128) {
                val += 1;
                if (!val || MSB(val, 7))
                        return 0; /* overflow */
                c = *buf++;
                val = (val << 7) + (c & 127);
        }
        *bufp = buf;
        return val;
}

int encode_varint(uintmax_t value, unsigned char *buf)
{
        unsigned char varint[16];
        unsigned pos = sizeof(varint) - 1;
        varint[pos] = value & 127;
        while (value >>= 7)
                varint[--pos] = 128 | (--value & 127);
        if (buf)
                memcpy(buf, varint + pos, sizeof(varint) - pos);
        return sizeof(varint) - pos;
}