/***********************************************************************/
/*                                                                     */
/*                           Objective Caml                            */
/*                                                                     */
/*            Xavier Leroy, projet Cristal, INRIA Rocquencourt         */
/*                                                                     */
/*  Copyright 1996 Institut National de Recherche en Informatique et   */
/*  Automatique.  Distributed only by permission.                      */
/*                                                                     */
/***********************************************************************/

/* $Id$ */

/* Structured input, compact format */

#include <string.h>
#include "alloc.h"
#include "fail.h"
#include "gc.h"
#include "intext.h"
#include "io.h"
#include "memory.h"
#include "mlvalues.h"
#include "misc.h"
#include "reverse.h"

static unsigned char * intern_input, * intern_src;
static int intern_input_malloced;
static header_t * intern_dest;
static asize_t obj_counter;
static value * intern_obj_table;
static unsigned int intern_color;
static header_t intern_header;
static value intern_block;

#define Sign_extend_shift ((sizeof(long) - 1) * 8)
#define Sign_extend(x) (((long)(x) << Sign_extend_shift) >> Sign_extend_shift)

#define read8u() (*intern_src++)
#define read8s() Sign_extend(*intern_src++)
#define read16u() \
  (intern_src += 2, \
   (intern_src[-2] << 8) + intern_src[-1])
#define read16s() \
  (intern_src += 2, \
   (Sign_extend(intern_src[-2]) << 8) + intern_src[-1])
#define read32u() \
  (intern_src += 4, \
   (intern_src[-4] << 24) + (intern_src[-3] << 16) + \
   (intern_src[-2] << 8) + intern_src[-1])
#define read32s() \
  (intern_src += 4, \
   (Sign_extend(intern_src[-4]) << 24) + (intern_src[-3] << 16) + \
   (intern_src[-2] << 8) + intern_src[-1])

#ifdef SIXTYFOUR
static long read64s()
{
  long res;
  int i;
  res = 0;
  for (i = 0; i < 8; i++) res = (res << 8) + intern_src[i];
  intern_src += 8;
  return res;
}
#endif

#define readblock(dest,len) \
  (bcopy(intern_src, dest, len), intern_src += len)

static void intern_cleanup()
{
  if (intern_input_malloced) stat_free((char *) intern_input);
  if (intern_obj_table != NULL) stat_free((char *) intern_obj_table);
  Hd_val(intern_block) = intern_header; /* Don't confuse the GC */
}

static void intern_rec(dest)
     value * dest;
{
  unsigned int code;
  tag_t tag;
  mlsize_t size, len, ofs_ind;
  value v;
  asize_t ofs;
  header_t header;

 tailcall:
  code = read8u();
  if (code >= PREFIX_SMALL_INT) {
    if (code >= PREFIX_SMALL_BLOCK) {
      /* Small block */
      tag = code & 0xF;
      size = (code >> 4) & 0x7;
    read_block:
      if (size == 0) {
        v = Atom(tag);
      } else {
        v = Val_hp(intern_dest);
        *dest = v;
        intern_obj_table[obj_counter++] = v;
        dest = (value *) (intern_dest + 1);
        *intern_dest = Make_header(size, tag, intern_color);
        intern_dest += 1 + size;
        for(/*nothing*/; size > 1; size--, dest++)
          intern_rec(dest);
        goto tailcall;
      }
    } else {
      /* Small integer */
      v = Val_int(code & 0x3F);
    }
  } else {
    if (code >= PREFIX_SMALL_STRING) {
      /* Small string */
      len = (code & 0x1F);
    read_string:
      size = (len + sizeof(value)) / sizeof(value);
      v = Val_hp(intern_dest);
      intern_obj_table[obj_counter++] = v;
      *intern_dest = Make_header(size, String_tag, intern_color);
      intern_dest += 1 + size;
      Field(v, size - 1) = 0;
      ofs_ind = Bsize_wsize(size) - 1;
      Byte(v, ofs_ind) = ofs_ind - len;
      readblock(String_val(v), len);
    } else {
      switch(code) {
      case CODE_INT8:
        v = Val_long(read8s());
        break;
      case CODE_INT16:
        v = Val_long(read16s());
        break;
      case CODE_INT32:
        v = Val_long(read32s());
        break;
      case CODE_INT64:
#ifdef SIXTYFOUR
        v = Val_long(read64s());
        break;
#else
        intern_cleanup();
        failwith("input_value: integer too large");
        break;
#endif
      case CODE_SHARED8:
        ofs = read8u();
      read_shared:
        Assert(ofs > 0 && ofs <= obj_counter); 
        v = intern_obj_table[obj_counter - ofs];
        break;
      case CODE_SHARED16:
        ofs = read16u();
        goto read_shared;
      case CODE_SHARED32:
        ofs = read32u();
        goto read_shared;
      case CODE_BLOCK32:
        header = (header_t) read32u();
        tag = Tag_hd(header);
        size = Wosize_hd(header);
        goto read_block;
      case CODE_STRING8:
        len = read8u();
        goto read_string;
      case CODE_STRING32:
        len = read32u();
        goto read_string;
      case CODE_DOUBLE_LITTLE:
      case CODE_DOUBLE_BIG:
        if (sizeof(double) != 8) {
          intern_cleanup();
          invalid_argument("input_value: non-standard floats");
        }
        v = Val_hp(intern_dest);
        intern_obj_table[obj_counter++] = v;
        *intern_dest = Make_header(Double_wosize, Double_tag, intern_color);
        intern_dest += 1 + Double_wosize;
        readblock((char *) v, 8);
        if (code != CODE_DOUBLE_NATIVE) Reverse_double(v);
        break;
      case CODE_DOUBLE_ARRAY8_LITTLE:
      case CODE_DOUBLE_ARRAY8_BIG:
        len = read8u();
      read_double_array:
        if (sizeof(double) != 8) {
          intern_cleanup();
          invalid_argument("input_value: non-standard floats");
        }
        size = len * Double_wosize;
        v = Val_hp(intern_dest);
        intern_obj_table[obj_counter++] = v;
        *intern_dest = Make_header(size, Double_array_tag, intern_color);
        intern_dest += 1 + size;
        readblock((char *) v, len * 8);
        if (code != CODE_DOUBLE_ARRAY8_NATIVE && 
            code != CODE_DOUBLE_ARRAY32_NATIVE) {
          mlsize_t i;
          for (i = 0; i < len; i++) Reverse_double((value)((double *)v + i));
        }
        break;
      case CODE_DOUBLE_ARRAY32_LITTLE:
      case CODE_DOUBLE_ARRAY32_BIG:
        len = read32u();
        goto read_double_array;
      }
    }
  }
  *dest = v;
}

static void intern_alloc(whsize, num_objects)
     mlsize_t whsize, num_objects;
{
  mlsize_t wosize;

  if (whsize == 0) {
    intern_obj_table = NULL;
  } else {
    wosize = Wosize_whsize(whsize);
    if (wosize > Max_wosize) failwith("intern: structure too big");
    if (wosize < Max_young_wosize)
      intern_block = alloc(wosize, String_tag);
    else
      intern_block = alloc_shr(wosize, String_tag);
    intern_header = Hd_val(intern_block);
    intern_color = Color_hd(intern_header);
    Assert (intern_color == White || intern_color == Black);
    intern_dest = (header_t *) Hp_val(intern_block);
    obj_counter = 0;
    intern_obj_table = (value *) stat_alloc(num_objects * sizeof(value));
  }
}

value input_value(chan)         /* ML */
     struct channel * chan;
{
  uint32 magic;
  mlsize_t block_len, num_objects, size_32, size_64, whsize;
  value res;

  magic = getword(chan);
  if (magic != Intext_magic_number) failwith("input_value: bad object");
  block_len = getword(chan);
  num_objects = getword(chan);
  size_32 = getword(chan);
  size_64 = getword(chan);
  /* Read block from channel */
  intern_input = (unsigned char *) stat_alloc(block_len);
  intern_input_malloced = 1;
  if (really_getblock(chan, (char *)intern_input, block_len) == 0) {
    stat_free((char *) intern_input);
    failwith("input_value: truncated object");
  }
  intern_src = intern_input;
  /* Allocate result */
#ifdef SIXTYFOUR
  whsize = size_64;
#else
  whsize = size_32;
#endif
  intern_alloc(whsize, num_objects);
  /* Fill it in */
  intern_rec(&res);
  /* Free everything */
  stat_free((char *) intern_input);
  if (intern_obj_table != NULL) stat_free((char *) intern_obj_table);
  return res;
}

value input_value_from_string(str, ofs) /* ML */
     value str, ofs;
{
  uint32 magic;
  mlsize_t block_len, num_objects, size_32, size_64, whsize;
  value res;
  Push_roots(r, 1);

  intern_src = &Byte_u(str, Long_val(ofs));
  intern_input_malloced = 0;
  magic = read32u();
  if (magic != Intext_magic_number) failwith("input_value: bad object");
  block_len = read32u();
  num_objects = read32u();
  size_32 = read32u();
  size_64 = read32u();
  /* Allocate result */
#ifdef SIXTYFOUR
  whsize = size_64;
#else
  whsize = size_32;
#endif
  r[0] = str;
  intern_alloc(whsize, num_objects);
  str = r[0];
  intern_src = &Byte_u(str, Long_val(ofs) + 5*4); /* If a GC occurred */
  /* Fill it in */
  intern_rec(&res);
  /* Free everything */
  if (intern_obj_table != NULL) stat_free((char *) intern_obj_table);
  /* Build result */
  r[0] = res;
  res = alloc_tuple(2);
  Field(res, 0) = r[0];
  Field(res, 1) = Val_long(Long_val(ofs) + 5*4 + block_len);
  Pop_roots();
  return res;
}