signed_leb128.c

static char SEGMENT_BITS = 0x7F; // 1111111
static char CONTINUE_BIT = 0x80; // 1000000
static char SIGN_BIT     = 0x40; // 0100000

void sleb128(int32_t x) {
    unsigned char buf;
    int negative = (x < 0);
    while(1) {
        buf = x & SEGMENT_BITS; // get the 7 (LSB?)
        x >>= 7;
        if (negative)
            x |= ((uint32_t)~0 << (32-7)); // if negative set the trailing bits as the sign (neg=1)
        
        if ((x == 0 && (buf & SIGN_BIT) == 0) || x == -1 && ((buf & SIGN_BIT) != 0)) {
            printf("0x%.2X ", buf);
            break;
        }
        buf |= CONTINUE_BIT;
        printf("0x%.2X ", buf);
    }
}