/* This file is part of limb                           https://lila.oss/limb
 * Copyright (C) 2023 Olivier Brunel                          jjk@jjacky.com */
/* SPDX-License-Identifier: GPL-2.0-only */
#include <limb/u64.h>

int
u64_pack_trim(char *dst_, size_t dlen, u64 val)
{
    u8 *dst = (u8 *) dst_;
    unsigned int bits = msb64(val);
    unsigned int b = 0;

    /* ensure little endianness */
    u64p_le(&val);

    for (;;) {
        int n = bits > 7 ? 7 : bits;
        /* enough room? */
        if (b >= dlen) return -1;
        /* store the 7 low bits */
        dst[b] = val & 127;
        /* and shift them out */
        val >>= 7;
        bits -= n;
        if (!bits)
            break;
        /* add our flag: one more byte */
        dst[b++] |= 128;
    }

    return b + 1;
}