/*
 * QuickJS Javascript Engine
 *
 * Copyright (c) 2017-2021 Fabrice Bellard
 * Copyright (c) 2017-2021 Charlie Gordon
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
#include "libc/bits/likely.h"
#include "third_party/quickjs/leb128.h"

asm(".ident\t\"\\n\\n\
QuickJS (MIT License)\\n\
Copyright (c) 2017-2021 Fabrice Bellard\\n\
Copyright (c) 2017-2021 Charlie Gordon\"");
asm(".include \"libc/disclaimer.inc\"");
/* clang-format off */

int get_leb128(uint32_t *pval, const uint8_t *buf, const uint8_t *buf_end)
{
    const uint8_t *ptr = buf;
    uint32_t v, a, i;
    v = 0;
    for(i = 0; i < 5; i++) {
        if (UNLIKELY(ptr >= buf_end))
            break;
        a = *ptr++;
        v |= (a & 0x7f) << (i * 7);
        if (!(a & 0x80)) {
            *pval = v;
            return ptr - buf;
        }
    }
    *pval = 0;
    return -1;
}

int get_sleb128(int32_t *pval, const uint8_t *buf, const uint8_t *buf_end)
{
    int ret;
    uint32_t val;
    ret = get_leb128(&val, buf, buf_end);
    if (ret < 0) {
        *pval = 0;
        return -1;
    }
    *pval = (val >> 1) ^ -(val & 1);
    return ret;
}