// SPDX-License-Identifier: 0BSD

///////////////////////////////////////////////////////////////////////////////

//

/// \file       vli_encoder.c

/// \brief      Encodes variable-length integers

//

//  Author:     Lasse Collin

//

///////////////////////////////////////////////////////////////////////////////

#include "common.h"

extern LZMA_API(lzma_ret)

lzma_vli_encode(lzma_vli vli, size_t *vli_pos,

    uint8_t *restrict out, size_t *restrict out_pos,

    size_t out_size)

{

  // If we haven't been given vli_pos, work in single-call mode.

  size_t vli_pos_internal = 0;

  if (vli_pos == NULL) {

    vli_pos = &vli_pos_internal;

    // In single-call mode, we expect that the caller has

    // reserved enough output space.

    if (*out_pos >= out_size)

      return LZMA_PROG_ERROR;

  } else {

    // This never happens when we are called by liblzma, but

    // may happen if called directly from an application.

    if (*out_pos >= out_size)

      return LZMA_BUF_ERROR;

  }

  // Validate the arguments.

  if (*vli_pos >= LZMA_VLI_BYTES_MAX || vli > LZMA_VLI_MAX)

    return LZMA_PROG_ERROR;

  // Shift vli so that the next bits to encode are the lowest. In

  // single-call mode this never changes vli since *vli_pos is zero.

  vli >>= *vli_pos * 7;

  // Write the non-last bytes in a loop.

  while (vli >= 0x80) {

    // We don't need *vli_pos during this function call anymore,

    // but update it here so that it is ready if we need to

    // return before the whole integer has been decoded.

    ++*vli_pos;

    assert(*vli_pos < LZMA_VLI_BYTES_MAX);

    // Write the next byte.

    out[*out_pos] = (uint8_t)(vli) | 0x80;

    vli >>= 7;

    if (++*out_pos == out_size)

      return vli_pos == &vli_pos_internal

          ? LZMA_PROG_ERROR : LZMA_OK;

  }

  // Write the last byte.

  out[*out_pos] = (uint8_t)(vli);

  ++*out_pos;

  ++*vli_pos;

  return vli_pos == &vli_pos_internal ? LZMA_OK : LZMA_STREAM_END;

}