/*----------------------------------------------------------------------*
 * IFFR.C  Support routines for reading IFF-85 files.          11/15/85
 * (IFF is Interchange Format File.)
 *
 * By Jerry Morrison and Steve Shaw, Electronic Arts.
 * This software is in the public domain.
 *
 * This version for the Commodore-Amiga computer.
 *----------------------------------------------------------------------*/
 
#include "iff.h"
/*  #include "DF1:iff/gio.h" */
/*  #define OFFSET_BEGINNING OFFSET_BEGINING */
 
/**  Manx expects INTs as 16 bits,  This wont matter on LAttice ***/
extern LONG Seek();
extern LONG Read();
 
/* ---------- Read -----------------------------------------------------*/
 
extern LONG PutID(); /**  Added as a diagnostic aid, will remove later ***/
 
/* ---------- OpenRIFF --------------------------------------------------*/
IFFP OpenRIFF(file0, new0, clientFrame)
   BPTR file0;   GroupContext *new0;   ClientFrame *clientFrame; {
    register BPTR file = file0;
    register GroupContext *new = new0;
    IFFP iffp = IFF_OKAY;
 
    new->parent       = NL;      /* "whole file" has no parent.*/
    new->clientFrame  = clientFrame;
    new->file         = file;
    new->position     = 0;
    new->ckHdr.ckID   = new->subtype    = NULL_CHUNK;
    new->ckHdr.ckSize = new->bytesSoFar = 0;
 
    /* Set new->bound. AmigaDOS specific code.*/
    if (file <= 0)   return(NO_FILE);
    Seek(file, 0L, OFFSET_END);         /* Seek to end of file.*/
    new->bound = Seek(file, 0L, OFFSET_CURRENT);   /* Pos'n == #bytes in file.*/
    if (new->bound < 0)   return(DOS_ERROR);   /* DOS being absurd.*/
    Seek(file, 0L, OFFSET_BEGINNING);      /* Go to file start.*/
    /* Would just do this if Amiga DOS maintained fh_End: */
    /* new->bound = (FileHandle *)BADDR(file)->fh_End; */
 
    if ( new->bound < (long)sizeof(ChunkHeader) )
   iffp = NOT_IFF;
    return(iffp);
    }
 
/* ---------- OpenRGroup -----------------------------------------------*/
IFFP OpenRGroup(parent0, new0)   GroupContext *parent0, *new0; {
    register GroupContext *parent = parent0;
    register GroupContext *new    = new0;
    IFFP iffp = IFF_OKAY;
 
    new->parent       = parent;
    new->clientFrame  = parent->clientFrame;
    new->file         = parent->file;
    new->position     = parent->position;
    new->bound        = parent->position + ChunkMoreBytes(parent);
    new->ckHdr.ckID   = new->subtype    = NULL_CHUNK;
    new->ckHdr.ckSize = new->bytesSoFar = 0;
 
    if ( new->bound > parent->bound  ||  IS_ODD(new->bound) )
   iffp = BAD_IFF;
    return(iffp);
    }
 
/* ---------- CloseRGroup -----------------------------------------------*/
IFFP CloseRGroup(context)   GroupContext *context; {
    register LONG position;
 
    if (context->parent == NL) {
   }  /* Context for whole file.*/
    else {
   position = context->position;
   context->parent->bytesSoFar += position - context->parent->position;
   context->parent->position = position;
   }
    return(IFF_OKAY);
    }
 
/* ---------- SkipFwd --------------------------------------------------*/
/* Skip over bytes in a context. Won't go backwards.*/
/* Updates context->position but not context->bytesSoFar.*/
/* This implementation is AmigaDOS specific.*/
IFFP SkipFwd(context, bytes)
 GroupContext *context;
 LONG bytes;
 {
    IFFP iffp = IFF_OKAY;
 
    if (bytes > 0) {
      if (-1 == Seek(context->file, bytes, OFFSET_CURRENT))
        iffp = BAD_IFF;   /* Ran out of bytes before chunk complete.*/
   else
       context->position += bytes;
   }
    return(iffp);
    }
 
/* ---------- GetChunkHdr ----------------------------------------------*/
ID GetChunkHdr(context0)
 GroupContext *context0;
 {
    register GroupContext *context = context0;
    register IFFP iffp;
    LONG remaining;
 
    /* Skip remainder of previous chunk & padding. */
    iffp = SkipFwd(context,
        ChunkMoreBytes(context) + IS_ODD(context->ckHdr.ckSize));
    CheckIFFP();
 
    /* Set up to read the new header. */
    context->ckHdr.ckID = BAD_IFF;   /* Until we know it's okay, mark it BAD.*/
    context->subtype    = NULL_CHUNK;
    context->bytesSoFar = 0;
 
    /* Generate a psuedo-chunk if at end-of-context. */
    remaining = context->bound - context->position;
    if (remaining == 0 ) {
        context->ckHdr.ckSize = 0;
        context->ckHdr.ckID   = END_MARK;
    }
    /* BAD_IFF if not enough bytes in the context for a ChunkHeader.*/
    else if ((long)sizeof(ChunkHeader) > remaining) {
         context->ckHdr.ckSize = remaining;
    }
 
    /* Read the chunk header (finally). */
    else {
        switch (Read(context->file,
                 &context->ckHdr, (long)sizeof(ChunkHeader)))
           {
           case -1: return(context->ckHdr.ckID = DOS_ERROR);
           case 0:  return(context->ckHdr.ckID = BAD_IFF);
           }
 
/*** $$$ ***
   PutID(context->ckHdr.ckID);
   printf("\n");
   printf("id = %lx\n", context->ckHdr.ckID);
**/
 
   /* Check: Top level chunk must be LIST or FORM or CAT. */
   if (context->parent == NL) {
       if (context->ckHdr.ckID != FORM &&
           context->ckHdr.ckID != LIST &&
           context->ckHdr.ckID != CAT )
           return(context->ckHdr.ckID = NOT_IFF);
   }
 
   /* Update the context. */
   context->position += (long)sizeof(ChunkHeader);
   remaining         -= (long)sizeof(ChunkHeader);
 
   /* Non-positive ID values are illegal and used for error codes.*/
   /* We could check for other illegal IDs...*/
   if (context->ckHdr.ckID <= 0 )
        context->ckHdr.ckID = BAD_IFF;
 
   /* Check: ckSize negative or larger than # bytes left in context? */
   else if (context->ckHdr.ckSize < 0  ||
       context->ckHdr.ckSize > remaining) {
       context->ckHdr.ckSize = remaining;
       context->ckHdr.ckID   = BAD_IFF;
       }
 
   /* Automatically read the LIST, FORM, PROP, or CAT subtype ID */
   else {
       if (context->ckHdr.ckID == LIST ||
           context->ckHdr.ckID == FORM ||
           context->ckHdr.ckID == PROP ||
           context->ckHdr.ckID == CAT) {
           iffp = IFFReadBytes(context, (BYTE *)&context->subtype,
                               (long)sizeof(ID));
           if (iffp != IFF_OKAY )
             context->ckHdr.ckID = iffp;
        }
     }
   }
   return(context->ckHdr.ckID);
 }
 
/* ---------- IFFReadBytes ---------------------------------------------*/
IFFP IFFReadBytes(context, buffer, nBytes)
  GroupContext *context;
  BYTE *buffer;
  LONG nBytes;
  {
      register IFFP iffp = IFF_OKAY;
 
    if (nBytes < 0)
       iffp = CLIENT_ERROR;
 
    else if (nBytes > ChunkMoreBytes(context))
       iffp = SHORT_CHUNK;
 
    else if (nBytes > 0 )
      switch ( Read(context->file, buffer, nBytes) ) {
         case -1: {iffp = DOS_ERROR; break; }
         case 0:  {iffp = BAD_IFF;   break; }
         default: {
                     context->position   += nBytes;
                     context->bytesSoFar += nBytes;
         }
     }
   return(iffp);
  }
 
/* ---------- SkipGroup ------------------------------------------------*/
IFFP SkipGroup(context)  GroupContext *context;  {
    }   /* Nothing to do, thanks to GetChunkHdr */
 
/* ---------- ReadIFF --------------------------------------------------*/
IFFP ReadIFF(file, clientFrame)
 BPTR file;
 ClientFrame *clientFrame;
 {
    /*CompilerBug register*/ IFFP iffp;
    GroupContext context;
 
    iffp = OpenRIFF(file, &context);
    context.clientFrame = clientFrame;
 
    if (iffp == IFF_OKAY) {
       iffp = GetChunkHdr(&context);
 
       if (iffp == FORM)
         iffp = (*clientFrame->getForm)(&context);
 
       else if (iffp == LIST)
         iffp = (*clientFrame->getList)(&context);
 
       else if (iffp == CAT)
         iffp = (*clientFrame->getCat)(&context);
    }
    CloseRGroup(&context);
 
    if (iffp > 0 )           /* Make sure we don't return an ID.*/
        iffp = NOT_IFF;      /* GetChunkHdr should've caught this.*/
    return(iffp);
    }
 
/* ---------- ReadIList ------------------------------------------------*/
IFFP ReadIList(parent, clientFrame)
  GroupContext *parent;
  ClientFrame *clientFrame;
  {
     GroupContext listContext;
     IFFP iffp;
     BOOL propOk = TRUE;
 
     iffp = OpenRGroup(parent, &listContext);
     CheckIFFP();
 
    /* One special case test lets us handle CATs as well as LISTs.*/
    if (parent->ckHdr.ckID == CAT)
       propOk = FALSE;
    else
       listContext.clientFrame = clientFrame;
 
    do {
        iffp = GetChunkHdr(&listContext);
           if (iffp == PROP) {
             if (propOk)
               iffp = (*clientFrame->getProp)(&listContext);
             else
               iffp = BAD_IFF;
           }
           else if (iffp == FORM)
              iffp = (*clientFrame->getForm)(&listContext);
 
           else if (iffp == LIST)
              iffp = (*clientFrame->getList)(&listContext);
 
           else if (iffp == CAT)
              iffp = (*clientFrame->getList)(&listContext);
 
       if (listContext.ckHdr.ckID != PROP)
           propOk = FALSE;   /* No PROPs allowed after this point.*/
   } while (iffp == IFF_OKAY);
 
    CloseRGroup(&listContext);
 
    if (iffp > 0 )   /* Only chunk types above are allowed in a LIST/CAT.*/
       iffp = BAD_IFF;
    return(iffp == END_MARK ? IFF_OKAY : iffp);
    }
 
/* ---------- ReadICat -------------------------------------------------*/
/* By special arrangement with the ReadIList implement'n, this is trivial.*/
IFFP ReadICat(parent)  GroupContext *parent;  {
    return( ReadIList(parent, NL) );
    }
 
/* ---------- GetFChunkHdr ---------------------------------------------*/
ID GetFChunkHdr(context)
 GroupContext *context;
 {
    register ID id;
 
    id = GetChunkHdr(context);
    if (id == PROP)
       context->ckHdr.ckID = id = BAD_IFF;
    return(id);
    }
 
/* ---------- GetF1ChunkHdr ---------------------------------------------*/
ID GetF1ChunkHdr(context)   GroupContext *context; {
    register ID id;
    register ClientFrame *clientFrame = context->clientFrame;
 
    id = GetChunkHdr(context);
    if (id == PROP)
       id = BAD_IFF;
 
    else if (id == FORM)
       id = (*clientFrame->getForm)(context);
 
    else if (id == LIST)
       id = (*clientFrame->getForm)(context);
 
    else if (id == CAT)
       id = (*clientFrame->getCat)(context);
 
    return(context->ckHdr.ckID = id);
  }
 
/* ---------- GetPChunkHdr ---------------------------------------------*/
ID GetPChunkHdr(context)
    GroupContext *context;
    {
    register ID id;
 
    id = GetChunkHdr(context);
    if (id == LIST || id == FORM || id == PROP || id == CAT )
       id = context->ckHdr.ckID = BAD_IFF;
    return(id);
    }