12.2.2.1.39. LZIO

12.2.2.1.39.1. lzio.h

/*
** $Id: lzio.h,v 1.31.1.1 2017/04/19 17:20:42 roberto Exp $
** Buffered streams
** See Copyright Notice in lua.h
*/


#ifndef lzio_h
#define lzio_h

#include "lua.h"

#include "lmem.h"


#define EOZ	(-1)			/* end of stream */

typedef struct Zio ZIO;

#define zgetc(z)  (((z)->n--)>0 ?  cast_uchar(*(z)->p++) : luaZ_fill(z))


typedef struct Mbuffer {
  char *buffer;
  size_t n;
  size_t buffsize;
} Mbuffer;

#define luaZ_initbuffer(L, buff) ((buff)->buffer = NULL, (buff)->buffsize = 0)

#define luaZ_buffer(buff)	((buff)->buffer)
#define luaZ_sizebuffer(buff)	((buff)->buffsize)
#define luaZ_bufflen(buff)	((buff)->n)

#define luaZ_buffremove(buff,i)	((buff)->n -= (i))
#define luaZ_resetbuffer(buff) ((buff)->n = 0)


#define luaZ_resizebuffer(L, buff, size) \
	((buff)->buffer = luaM_reallocvchar(L, (buff)->buffer, \
				(buff)->buffsize, size), \
	(buff)->buffsize = size)

#define luaZ_freebuffer(L, buff)	luaZ_resizebuffer(L, buff, 0)


LUAI_FUNC void luaZ_init (lua_State *L, ZIO *z, lua_Reader reader,
                                        void *data);
LUAI_FUNC size_t luaZ_read (ZIO* z, void *b, size_t n);	/* read next n bytes */



/* --------- Private Part ------------------ */

struct Zio {
  size_t n;			/* bytes still unread */
  const char *p;		/* current position in buffer */
  lua_Reader reader;		/* reader function */
  void *data;			/* additional data */
  lua_State *L;			/* Lua state (for reader) */
};


LUAI_FUNC int luaZ_fill (ZIO *z);

#endif

---

12.2.2.1.39.2. lzio.c

/*
** $Id: lzio.c,v 1.37.1.1 2017/04/19 17:20:42 roberto Exp $
** Buffered streams
** See Copyright Notice in lua.h
*/

#define lzio_c
#define LUA_CORE

#include "lprefix.h"


#include <string.h>

#include "lua.h"

#include "llimits.h"
#include "lmem.h"
#include "lstate.h"
#include "lzio.h"


int luaZ_fill (ZIO *z) {
  size_t size;
  lua_State *L = z->L;
  const char *buff;
  lua_unlock(L);
  buff = z->reader(L, z->data, &size);
  lua_lock(L);
  if (buff == NULL || size == 0)
    return EOZ;
  z->n = size - 1;  /* discount char being returned */
  z->p = buff;
  return cast_uchar(*(z->p++));
}


void luaZ_init (lua_State *L, ZIO *z, lua_Reader reader, void *data) {
  z->L = L;
  z->reader = reader;
  z->data = data;
  z->n = 0;
  z->p = NULL;
}


/* --------------------------------------------------------------- read --- */
size_t luaZ_read (ZIO *z, void *b, size_t n) {
  while (n) {
    size_t m;
    if (z->n == 0) {  /* no bytes in buffer? */
      if (luaZ_fill(z) == EOZ)  /* try to read more */
        return n;  /* no more input; return number of missing bytes */
      else {
        z->n++;  /* luaZ_fill consumed first byte; put it back */
        z->p--;
      }
    }
    m = (n <= z->n) ? n : z->n;  /* min. between n and z->n */
    memcpy(b, z->p, m);
    z->n -= m;
    z->p += m;
    b = (char *)b + m;
    n -= m;
  }
  return 0;
}