gistfile1.c

U0 ArcExpandBuf(ArcCs *c)
//Use ExpandBuf() unless you know what
//you're doing.
{
  U8 *dst_ptr,*dst_limit;
  U64 basecode,lastcode,code;
  ArcTableEntry *temp,*temp1;

  dst_ptr=c->dst_buf+c->dst_pos;
  dst_limit=c->dst_buf+c->dst_size;

  while (dst_ptr<dst_limit &&
         c->stk_ptr!=c->stk_base)
    *dst_ptr++ = * -- c->stk_ptr;

  if (c->stk_ptr==c->stk_base && dst_ptr<dst_limit) {
    if (c->saved_basecode==MAX_U32) {
      lastcode=BFieldExtU32(c->src_buf,c->src_pos,
         c->next_bits_in_use);
      c->src_pos+=c->next_bits_in_use;
      *dst_ptr++=lastcode;
      ArcGetTableEntry(c);
      c->last_ch=lastcode;
    } else
      lastcode=c->saved_basecode;
    while (dst_ptr<dst_limit &&
      c->src_pos+c->next_bits_in_use<=c->src_size) {
      basecode=BFieldExtU32(c->src_buf,c->src_pos,
         c->next_bits_in_use);
      c->src_pos+=c->next_bits_in_use;
      if (c->cur_entry==&c->compress[basecode]) {
        *c->stk_ptr++=c->last_ch;
        code=lastcode;
      } else
        code=basecode;
      while (code>=c->min_table_entry) {
        *c->stk_ptr++=c->compress[code].ch;
        code=c->compress[code].basecode;
      }
      *c->stk_ptr++=code;
      c->last_ch=code;

      c->entry_used=TRUE;
      temp=c->cur_entry;
      temp->basecode=lastcode;
      temp->ch=c->last_ch;
      temp1=&c->hash[lastcode];
      temp->next=temp1->next;
      temp1->next=temp;

      ArcGetTableEntry(c);
      while (dst_ptr<dst_limit && c->stk_ptr!=c->stk_base)
        *dst_ptr++ = * -- c->stk_ptr;
      lastcode=basecode;
    }
    c->saved_basecode=lastcode;
  }
  c->dst_pos=dst_ptr-c->dst_buf;
}

ArcCs *ArcCsNew(BoolI8 expand,BoolI8 text_only)
{
  ArcCs *c;
  c=CAlloc(sizeof(ArcCs));
  if (expand) {
    c->stk_base=MAlloc(ARC_MAX_TABLE_ENTRY+1);
    c->stk_ptr=c->stk_base;
  }
  if (text_only)
    c->min_bits=7;
  else
    c->min_bits=8;
  c->min_table_entry=1<<c->min_bits;
  c->free_index=c->min_table_entry;
  c->next_bits_in_use=c->min_bits+1;
  c->free_limit=1<<c->next_bits_in_use;
  c->saved_basecode=MAX_U32;
  c->entry_used=TRUE;
  ArcGetTableEntry(c);
  c->entry_used=TRUE;
  return c;
}

U0 ArcCsDel(ArcCs *c)
{
  Free(c->stk_base);
  Free(c);
}


ArcCompressStruct *CompressBuf(U8 *src,U64 size,
                U64 flags=0,TaskStruct *mem_task=NULL)
{
  U64 size_out;
  ArcCompressStruct *result;
  BoolI8 text_only=ArcDetermineCompressionType(src,size)==CT_7_BIT;
  ArcCs *c=ArcCsNew(FALSE,text_only);
  c->src_size=size;
  c->src_buf=src;
  c->dst_size=(size+sizeof(ArcCompressStruct))<<3;
  c->dst_buf=CAlloc(c->dst_size>>3);
  c->dst_pos=sizeof(ArcCompressStruct)<<3;
  ArcCompressBuf(c);
  ArcFinishCompression(c);
  if (c->src_pos==c->src_size) {
    size_out=(c->dst_pos+7)>>3;
    result=MAlloc(size_out,mem_task);
    MemCpy(result,c->dst_buf,size_out);
    result->compression_type=text_only ? CT_7_BIT:CT_8_BIT;
    result->compressed_size=size_out;
  } else {
    result=MAlloc(size+sizeof(ArcCompressStruct),mem_task);
    MemCpy(&result->body,src,size);
    result->compression_type=CT_NONE;
    result->compressed_size=size+sizeof(ArcCompressStruct);
  }
  result->expanded_size=size;
  result->flags=flags;
  Free(c->dst_buf);
  ArcCsDel(c);
  return result;
}

U8 *ExpandBuf(ArcCompressStruct *r,TaskStruct *mem_task=NULL)
{
  ArcCs *c;
  U8 *result;
  BoolI8 text_only;
  result=MAlloc(r->expanded_size+1,mem_task);
  result[r->expanded_size]=0; //terminate
  text_only= r->compression_type==CT_7_BIT;
  if (r->compression_type==CT_NONE) {
    MemCpy(result,&r->body,r->expanded_size);
    goto expand_end;
  }
  c=ArcCsNew(TRUE,text_only);
  c->src_size=r->compressed_size<<3;
  c->src_pos=sizeof(ArcCompressStruct)<<3;
  c->src_buf=r;
  c->dst_size=r->expanded_size;
  c->dst_buf=result;
  c->dst_pos=0;
  ArcExpandBuf(c);
  ArcCsDel(c);

expand_end:
  return result;
}