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365 lines
13 KiB
365 lines
13 KiB
/* mmioriff.c
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*
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* MMIO RIFF functions.
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*/
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#include <windows.h>
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#include "mmsystem.h"
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#include "mmsysi.h"
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#include "mmioi.h"
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#define BCODE BYTE _based(_segname("_CODE"))
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static BCODE bPad;
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/* @doc EXTERNAL
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@api UINT | mmioDescend | This function descends into a chunk of a
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RIFF file opened with <f mmioOpen>. It can also search for a given
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chunk.
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@parm HMMIO | hmmio | Specifies the file handle of an open RIFF file.
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@parm LPMMCKINFO | lpck | Specifies a far pointer to a
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caller-supplied <t MMCKINFO> structure that <f mmioDescend> fills
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with the following information:
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-- The <e MMCKINFO.ckid> field is the chunk ID of the chunk.
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-- The <e MMCKINFO.cksize> field is the size of the data portion
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of the chunk. The data size includes the form type or list type (if
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any), but does not include the 8-byte chunk header or the pad byte at
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the end of the data (if any).
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-- The <e MMCKINFO.fccType> field is the form type if
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<e MMCKINFO.ckid> is "RIFF", or the list type if
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<e MMCKINFO.ckid> is "LIST". Otherwise, it is NULL.
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-- The <e MMCKINFO.dwDataOffset> field is the file offset of the
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beginning of the data portion of the chunk. If the chunk is a
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"RIFF" chunk or a "LIST" chunk, then <e MMCKINFO.dwDataOffset>
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is the offset of the form type or list type.
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-- The <e MMCKINFO.dwFlags> contains other information about the chunk.
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Currently, this information is not used and is set to zero.
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If the MMIO_FINDCHUNK, MMIO_FINDRIFF, or MMIO_FINDLIST flag is
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specified for <p wFlags>, then the <t MMCKINFO> structure is also
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used to pass parameters to <f mmioDescend>:
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-- The <e MMCKINFO.ckid> field specifies the four-character code
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of the chunk ID, form type, or list type to search for.
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@parm LPMMCKINFO | lpckParent | Specifies a far pointer to an
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optional caller-supplied <t MMCKINFO> structure identifying
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the parent of the chunk being searched for.
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A parent of a chunk is the enclosing chunk--only "RIFF" and "LIST"
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chunks can be parents. If <p lpckParent> is not NULL, then
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<f mmioDescend> assumes the <t MMCKINFO> structure it refers to
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was filled when <f mmioDescend> was called to descend into the parent
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chunk, and <f mmioDescend> will only search for a chunk within the
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parent chunk. Set <p lpckParent> to NULL if no parent chunk is
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being specified.
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@parm UINT | wFlags | Specifies search options. Contains up to one
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of the following flags. If no flags are specified,
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<f mmioDescend> descends into the chunk beginning at the current file
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position.
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@flag MMIO_FINDCHUNK | Searches for a chunk with the specified chunk ID.
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@flag MMIO_FINDRIFF | Searches for a chunk with chunk ID "RIFF"
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and with the specified form type.
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@flag MMIO_FINDLIST | Searches for a chunk with chunk ID "LIST"
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and with the specified form type.
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@rdesc The return value is zero if the function is successful.
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Otherwise, the return value specifies an error code. If the end of
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the file (or the end of the parent chunk, if given) is reached before
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the desired chunk is found, the return value is
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MMIOERR_CHUNKNOTFOUND.
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@comm A RIFF chunk consists of a four-byte chunk ID (type FOURCC),
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followed by a four-byte chunk size (type DWORD), followed
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by the data portion of the chunk, followed by a null pad byte if
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the size of the data portion is odd. If the chunk ID is "RIFF" or
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"LIST", the first four bytes of the data portion of the chunk are
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a form type or list type (type FOURCC).
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If <f mmioDescend> is used to search for a chunk, the file
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position should be at the beginning of a
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chunk before calling <f mmioDescend>. The search begins at the
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current file position and continues to the end of the file. If a
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parent chunk is specified, the file position should be somewhere
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within the parent chunk before calling <f mmioDescend>. In this case,
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the search begins at the current file position and continues to the
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end of the parent chunk.
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If <f mmioDescend> is unsuccessful in searching for a chunk, the
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current file position is undefined. If <f mmioDescend> is
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successful, the current file position is changed. If the chunk
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is a "RIFF" or "LIST" chunk, the new file position
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will be just after the form type or list type (12 bytes from the
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beginning of the chunk). For other chunks, the new file position will be
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the start of the data portion of the chunk (8 bytes from the
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beginning of the chunk).
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For efficient RIFF file I/O, use buffered I/O.
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@xref mmioAscend MMCKINFO
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*/
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UINT WINAPI
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mmioDescend(HMMIO hmmio, LPMMCKINFO lpck, const MMCKINFO FAR* lpckParent, UINT wFlags)
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{
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FOURCC ckidFind; // chunk ID to find (or NULL)
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FOURCC fccTypeFind; // form/list type to find (or NULL)
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V_FLAGS(wFlags, MMIO_DESCEND_VALID, mmioDescend, MMSYSERR_INVALFLAG);
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V_WPOINTER(lpck, sizeof(MMCKINFO), MMSYSERR_INVALPARAM);
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V_RPOINTER0(lpckParent, sizeof(MMCKINFO), MMSYSERR_INVALPARAM);
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/* figure out what chunk id and form/list type to search for */
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if (wFlags & MMIO_FINDCHUNK)
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ckidFind = lpck->ckid, fccTypeFind = NULL;
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else
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if (wFlags & MMIO_FINDRIFF)
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ckidFind = FOURCC_RIFF, fccTypeFind = lpck->fccType;
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else
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if (wFlags & MMIO_FINDLIST)
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ckidFind = FOURCC_LIST, fccTypeFind = lpck->fccType;
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else
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ckidFind = fccTypeFind = NULL;
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lpck->dwFlags = 0L;
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while (TRUE)
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{
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UINT w;
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/* read the chunk header */
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if (mmioRead(hmmio, (HPSTR) lpck, 2 * sizeof(DWORD)) !=
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2 * sizeof(DWORD))
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return MMIOERR_CHUNKNOTFOUND;
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/* store the offset of the data part of the chunk */
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if ((lpck->dwDataOffset = mmioSeek(hmmio, 0L, SEEK_CUR)) == -1)
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return MMIOERR_CANNOTSEEK;
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/* see if the chunk is within the parent chunk (if given) */
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if ((lpckParent != NULL) &&
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(lpck->dwDataOffset - 8L >=
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lpckParent->dwDataOffset + lpckParent->cksize))
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return MMIOERR_CHUNKNOTFOUND;
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/* if the chunk if a 'RIFF' or 'LIST' chunk, read the
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* form type or list type
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*/
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if ((lpck->ckid == FOURCC_RIFF) || (lpck->ckid == FOURCC_LIST))
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{
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if (mmioRead(hmmio, (HPSTR) &lpck->fccType,
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sizeof(DWORD)) != sizeof(DWORD))
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return MMIOERR_CHUNKNOTFOUND;
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}
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else
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lpck->fccType = NULL;
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/* if this is the chunk we're looking for, stop looking */
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if ( ((ckidFind == NULL) || (ckidFind == lpck->ckid)) &&
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((fccTypeFind == NULL) || (fccTypeFind == lpck->fccType)) )
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break;
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/* ascend out of the chunk and try again */
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if ((w = mmioAscend(hmmio, lpck, 0)) != 0)
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return w;
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}
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return 0;
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}
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/* @doc EXTERNAL
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@api UINT | mmioAscend | This function ascends out of a chunk in a
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RIFF file descended into with <f mmioDescend> or created with
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<f mmioCreateChunk>.
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@parm HMMIO | hmmio | Specifies the file handle of an open RIFF file.
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@parm LPMMCKINFO | lpck | Specifies a far pointer to a
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caller-supplied <t MMCKINFO> structure previously filled by
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<f mmioDescend> or <f mmioCreateChunk>.
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@parm UINT | wFlags | Is not used and should be set to zero.
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@rdesc The return value is zero if the function is successful.
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Otherwise, the return value specifies an error code. The error
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code can be one of the following codes:
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@flag MMIOERR_CANNOTWRITE | The contents of the buffer could
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not be written to disk.
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@flag MMIOERR_CANNOTSEEK | There was an error while seeking to
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the end of the chunk.
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@comm If the chunk was descended into using <f mmioDescend>, then
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<f mmioAscend> seeks to the location following the end of the
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chunk (past the extra pad byte, if any).
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If the chunk was created and descended into using
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<f mmioCreateChunk>, or if the MMIO_DIRTY flag is set in the
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<e MMCKINFO.dwFlags> field of the <t MMCKINFO> structure
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referenced by <p lpck>, then the current file position
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is assumed to be the end of the data portion of the chunk.
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If the chunk size is not the same as the value stored
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in the <e MMCKINFO.cksize> field when <f mmioCreateChunk>
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was called, then <f mmioAscend> corrects the chunk
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size in the file before ascending from the chunk. If the chunk
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size is odd, <f mmioAscend> writes a null pad byte at the end of the
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chunk. After ascending from the chunk, the current file position is
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the location following the end of the chunk (past the extra pad byte,
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if any).
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@xref mmioDescend mmioCreateChunk MMCKINFO
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*/
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UINT WINAPI
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mmioAscend(HMMIO hmmio, LPMMCKINFO lpck, UINT wFlags)
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{
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V_FLAGS(wFlags, 0, mmioAscend, MMSYSERR_INVALFLAG);
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V_WPOINTER(lpck, sizeof(MMCKINFO), MMSYSERR_INVALPARAM);
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if (lpck->dwFlags & MMIO_DIRTY)
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{
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/* <lpck> refers to a chunk created by mmioCreateChunk();
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* check that the chunk size that was written when
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* mmioCreateChunk() was called is the real chunk size;
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* if not, fix it
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*/
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LONG lOffset; // current offset in file
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LONG lActualSize; // actual size of chunk data
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if ((lOffset = mmioSeek(hmmio, 0L, SEEK_CUR)) == -1)
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return MMIOERR_CANNOTSEEK;
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if ((lActualSize = lOffset - lpck->dwDataOffset) < 0)
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return MMIOERR_CANNOTWRITE;
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if (LOWORD(lActualSize) & 1)
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{
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/* chunk size is odd -- write a null pad byte */
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if (mmioWrite(hmmio, (HPSTR) &bPad, sizeof(bPad))
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!= sizeof(bPad))
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return MMIOERR_CANNOTWRITE;
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}
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if (lpck->cksize == (DWORD)lActualSize)
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return 0;
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/* fix the chunk header */
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lpck->cksize = lActualSize;
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if (mmioSeek(hmmio, lpck->dwDataOffset
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- sizeof(DWORD), SEEK_SET) == -1)
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return MMIOERR_CANNOTSEEK;
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if (mmioWrite(hmmio, (HPSTR) &lpck->cksize,
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sizeof(DWORD)) != sizeof(DWORD))
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return MMIOERR_CANNOTWRITE;
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}
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/* seek to the end of the chunk, past the null pad byte
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* (which is only there if chunk size is odd)
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*/
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if (mmioSeek(hmmio, lpck->dwDataOffset + lpck->cksize
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+ (lpck->cksize & 1L), SEEK_SET) == -1)
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return MMIOERR_CANNOTSEEK;
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return 0;
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}
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/* @doc EXTERNAL
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@api UINT | mmioCreateChunk | This function creates a chunk in a
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RIFF file opened with <f mmioOpen>. The new chunk is created at the
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current file position. After the new chunk is created, the current
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file position is the beginning of the data portion of the new chunk.
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@parm HMMIO | hmmio | Specifies the file handle of an open RIFF
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file.
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@parm LPMMCKINFO | lpck | Specifies a pointer to a caller-supplied
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<t MMCKINFO> structure containing information about the chunk to be
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created. The <t MMCKINFO> structure should be set up as follows:
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-- The <e MMCKINFO.ckid> field specifies the chunk ID of the
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chunk. If <p wFlags> includes MMIO_CREATERIFF or MMIO_CREATELIST,
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this field will be filled by <f mmioCreateChunk>.
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-- The <e MMCKINFO.cksize> field specifies the size of the data
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portion of the chunk, including the form type or list type (if any).
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If this value is not correct when <f mmioAscend> is called to mark
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the end of the chunk, them <f mmioAscend> will correct the chunk
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size.
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-- The <e MMCKINFO.fccType> field specifies the form type or list
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type if the chunk is a "RIFF" or "LIST" chunk. If the chunk is not a
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"RIFF" or "LIST" chunk, this field need not be filled in.
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-- The <e MMCKINFO.dwDataOffset> field need not be filled in. The
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<f mmioCreateChunk> function will fill this field with the file
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offset of the data portion of the chunk.
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-- The <e MMCKINFO.dwFlags> field need not be filled in. The
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<f mmioCreateChunk> function will set the MMIO_DIRTY flag in
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<e MMCKINFO.dwFlags>.
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@parm UINT | wFlags | Specifies flags to optionally create either a
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"RIFF" chunk or a "LIST" chunk. Can contain one of the following
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flags:
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@flag MMIO_CREATERIFF | Creates a "RIFF" chunk.
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@flag MMIO_CREATELIST | Creates a "LIST" chunk.
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@rdesc The return value is zero if the function is successful.
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Otherwise, the return value specifies an error code. The error
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code can be one of the following codes:
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@flag MMIOERR_CANNOTWRITE | Unable to write the chunk header.
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@flag MMIOERR_CANNOTSEEK | Uanble to determine offset of data
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portion of the chunk.
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@comm This function cannot insert a chunk into the middle of a
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file. If a chunk is created anywhere but the end of a file,
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<f mmioCreateChunk> will overwrite existing information in the file.
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*/
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UINT WINAPI
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mmioCreateChunk(HMMIO hmmio, LPMMCKINFO lpck, UINT wFlags)
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{
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int iBytes; // bytes to write
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LONG lOffset; // current offset in file
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V_FLAGS(wFlags, MMIO_CREATE_VALID, mmioCreateChunk, MMSYSERR_INVALFLAG);
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V_WPOINTER(lpck, sizeof(MMCKINFO), MMSYSERR_INVALPARAM);
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/* store the offset of the data part of the chunk */
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if ((lOffset = mmioSeek(hmmio, 0L, SEEK_CUR)) == -1)
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return MMIOERR_CANNOTSEEK;
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lpck->dwDataOffset = lOffset + 2 * sizeof(DWORD);
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/* figure out if a form/list type needs to be written */
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if (wFlags & MMIO_CREATERIFF)
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lpck->ckid = FOURCC_RIFF, iBytes = 3 * sizeof(DWORD);
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else
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if (wFlags & MMIO_CREATELIST)
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lpck->ckid = FOURCC_LIST, iBytes = 3 * sizeof(DWORD);
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else
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iBytes = 2 * sizeof(DWORD);
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/* write the chunk header */
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if (mmioWrite(hmmio, (HPSTR) lpck, (LONG) iBytes) != (LONG) iBytes)
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return MMIOERR_CANNOTWRITE;
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lpck->dwFlags = MMIO_DIRTY;
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return 0;
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}
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