shithub: sox

ref: 07b47062af734cdf690a7f72e8546188a207295e
dir: /src/luaform.c/

/*
 * luafile - file formats in Lua.
 *
 * Copyright 2006-2007 Reuben Thomas
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library. If not, write to the Free Software
 * Foundation, Fifth Floor, 51 Franklin Street, Boston, MA 02111-1301,
 * USA.  */

 
#include "st_i.h"

#include <string.h>
#include <lua.h>
#include <lauxlib.h>

/* Private data */
typedef struct luafile {
  lua_State *L;                 /* Lua state */
  int scriptref;                /* reference to script function */
} *lua_t;

assert_static(sizeof(struct luafile) <= ST_MAX_FILE_PRIVSIZE, 
              /* else */ skel_PRIVSIZE_too_big);

/*
 * Set up Lua state and read script.
 */
static int lua_start(ft_t ft)
{
  lua_t lua = (lua_t)ft->priv;
  int ret;

  lua->L = st_lua_new();

  if (!ft->signal.lua_script) {
    st_fail("no Lua script given");
    return ST_EOF;
  } else if ((ret = luaL_loadfile(lua->L, ft->signal.lua_script)) != 0) {
    st_fail("cannot load Lua script %s: error %d", ft->signal.lua_script, ret);
    return ST_EOF;
  }
  fprintf(stderr, "type %d\n", lua_type(lua->L, -1));
  lua->scriptref = luaL_ref(lua->L, LUA_REGISTRYINDEX);

  return ST_SUCCESS;
}

/*
 * Call Lua script with (action, fp, array), and return return value
 * (an st_size_t) to the caller.
 */
static st_size_t lua_callscript(lua_t lua)
{
  st_size_t done;
  int ret;

  lua_rawgeti(lua->L, LUA_REGISTRYINDEX, lua->scriptref);
  if ((ret = lua_pcall(lua->L, 3, 1, 0)) != 0)
    st_fail("error in Lua script: %d", ret);
  done = lua_tointeger(lua->L, -1);
  lua_pop(lua->L, 1);

  return done;
}

/*
 * Read up to len samples of type st_sample_t from file into buf[].
 * Return number of samples read.
 */
static st_size_t lua_read(ft_t ft, st_sample_t *buf, st_size_t len)
{
  lua_t lua = (lua_t)ft->priv;
  st_sample_t_array_t inarr;

  inarr.size = len;
  inarr.data = buf;

  lua_pushstring(lua->L, "read");
  st_lua_pushfile(lua->L, ft->fp);
  st_lua_pusharray(lua->L, inarr);

  return lua_callscript(lua);
}

/*
 * Write len samples of type st_sample_t from buf[] to file.
 * Return number of samples written.
 */
static st_size_t lua_write(ft_t ft, const st_sample_t *buf, st_size_t len)
{
  lua_t lua = (lua_t)ft->priv;
  st_sample_t_array_t outarr;

  outarr.size = len;
  outarr.data = (st_sample_t *)buf;

  lua_pushstring(lua->L, "write");
  st_lua_pushfile(lua->L, ft->fp);
  st_lua_pusharray(lua->L, outarr);

  return lua_callscript(lua);
}

/*
 * Clean up state.
 */
static int lua_stop(ft_t ft)
{
  lua_t lua = (lua_t)ft->priv;

  lua_close(lua->L);

  return ST_SUCCESS;
}

/* Seek relative to current position. */
static int lua_seek(ft_t ft, st_size_t offset)
{
  lua_t lua = (lua_t)ft->priv;

  lua_pushstring(lua->L, "seek");
  st_lua_pushfile(lua->L, ft->fp);
  lua_pushinteger(lua->L, offset);

  return lua_callscript(lua);
}

/* Format file suffixes */
static const char *lua_names[] = {
  "lua",
  NULL
};

/* Format descriptor */
static st_format_t st_lua_format = {
  lua_names,
  NULL,
  0,
  lua_start,
  lua_read,
  lua_stop,
  lua_start,
  lua_write,
  lua_stop,
  lua_seek
};

/*
 * Function returning effect descriptor. This should be the only
 * externally visible object.
 */
const st_format_t *st_lua_format_fn(void)
{
  return &st_lua_format;
}