dma.h File Reference

Wrapper functions for direct memory access hardware. More...

#include "nds/ndstypes.h"

Functions
int	dmaBusy (uint8 channel)
	determines if the specified channel is busy
void	dmaCopy (const void *source, void *dest, uint32 size)
	copies from source to destination using channel 3 of DMA available channels in half words
void	dmaCopyAsynch (const void *source, void *dest, uint32 size)
	copies from source to destination using channel 3 of DMA available channels in half words. This function returns immediately after starting the transfer.
void	dmaCopyHalfWords (uint8 channel, const void *src, void *dest, uint32 size)
	copies from source to destination on one of the 4 available channels in half words
void	dmaCopyHalfWordsAsynch (uint8 channel, const void *src, void *dest, uint32 size)
	copies from source to destination on one of the 4 available channels in half words. This function returns immediately after starting the transfer.
void	dmaCopyWords (uint8 channel, const void *src, void *dest, uint32 size)
	copies from source to destination on one of the 4 available channels in words
void	dmaCopyWordsAsynch (uint8 channel, const void *src, void *dest, uint32 size)
	copies from source to destination on one of the 4 available channels in half words. This function returns immediately after starting the transfer.
void	dmaFillHalfWords (u16 value, void *dest, uint32 size)
	fills the source with the supplied value using DMA channel 3
void	dmaFillWords (u32 value, void *dest, uint32 size)
	fills the source with the supplied value using DMA channel 3

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Detailed Description

Wrapper functions for direct memory access hardware.

The DS has 4 hardware direct memory access devices per CPU which can be used to transfer or fill chunks of memeory without CPU intervention. Utilizing DMA is generaly faster than CPU copies (memcpy, swiCopy, for loops, etc..).

DMA has no access to data caches on the DS and as such will give unexpected results when DMAing data from main memory. The cache must be flushed as follows when using DMA to ensure proper opertion on the arm9:

DC_FlushRange(source, sizeof(dataToCopy));
dmaCopy(source, destination, sizeof(dataToCopy));

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Function Documentation

static dmaBusy

(

uint8

channel

)

[inline]

determines if the specified channel is busy

Parameters:

channel

the dma channel to check (0 - 3).

Returns:

non zero if busy, 0 if channel is free

static void dmaCopy	(	const void *	source,
		void *	dest,
		uint32	size
	)		[inline]

copies from source to destination using channel 3 of DMA available channels in half words

Parameters:

source	the source to copy from
dest	the destination to copy to
size	the size in bytes of the data to copy. Will be truncated to the nearest half word (2 bytes)

Examples:

audio/maxmod/song_events_example/source/template.c, audio/micrecord/source/micrecord.c, capture/ScreenShot/source/main.cpp, capture/ScreenShot/source/screenshot.cpp, Graphics/Backgrounds/256_color_bmp/source/main.cpp, Graphics/Backgrounds/all_in_one/source/advanced.cpp, Graphics/Backgrounds/all_in_one/source/basic.cpp, Graphics/Backgrounds/all_in_one/source/handmade.cpp, Graphics/Backgrounds/all_in_one/source/scrolling.cpp, Graphics/Backgrounds/rotation/source/main.cpp, and Graphics/Sprites/animate_simple/source/template.c.

static void dmaCopyAsynch	(	const void *	src,
		void *	dest,
		uint32	size
	)		[inline]

copies from source to destination using channel 3 of DMA available channels in half words. This function returns immediately after starting the transfer.

Parameters:

src	the source to copy from
dest	the destination to copy to
size	the size in bytes of the data to copy. Will be truncated to the nearest half word (2 bytes)

static void dmaCopyHalfWords	(	uint8	channel,
		const void *	src,
		void *	dest,
		uint32	size
	)		[inline]

copies from source to destination on one of the 4 available channels in half words

Parameters:

channel	the dma channel to use (0 - 3).
src	the source to copy from
dest	the destination to copy to
size	the size in bytes of the data to copy. Will be truncated to the nearest half word (2 bytes)

static void dmaCopyHalfWordsAsynch	(	uint8	channel,
		const void *	src,
		void *	dest,
		uint32	size
	)		[inline]

copies from source to destination on one of the 4 available channels in half words. This function returns immediately after starting the transfer.

Parameters:

channel	the dma channel to use (0 - 3).
src	the source to copy from
dest	the destination to copy to
size	the size in bytes of the data to copy. Will be truncated to the nearest half word (2 bytes)

static void dmaCopyWords	(	uint8	channel,
		const void *	src,
		void *	dest,
		uint32	size
	)		[inline]

copies from source to destination on one of the 4 available channels in words

Parameters:

channel	the dma channel to use (0 - 3).
src	the source to copy from
dest	the destination to copy to
size	the size in bytes of the data to copy. Will be truncated to the nearest word (4 bytes)

static void dmaCopyWordsAsynch	(	uint8	channel,
		const void *	src,
		void *	dest,
		uint32	size
	)		[inline]

copies from source to destination on one of the 4 available channels in half words. This function returns immediately after starting the transfer.

Parameters:

channel	the dma channel to use (0 - 3).
src	the source to copy from
dest	the destination to copy to
size	the size in bytes of the data to copy. Will be truncated to the nearest word (4 bytes)

static void dmaFillHalfWords	(	u16	value,
		void *	dest,
		uint32	size
	)		[inline]

fills the source with the supplied value using DMA channel 3

Parameters:

value	the 16 byte value to fill memory with
dest	the destination to copy to
size	the size in bytes of the area to fill. Will be truncated to the nearest half word (2 bytes)

Examples:

audio/maxmod/song_events_example2/source/template.c, and Graphics/Sprites/bitmap_sprites/source/main.cpp.

static void dmaFillWords	(	u32	value,
		void *	dest,
		uint32	size
	)		[inline]

fills the source with the supplied value using DMA channel 3

Parameters:

value	the 32 byte value to fill memory with
dest	the destination to copy to
size	the size in bytes of the area to fill. Will be truncated to the nearest word (4 bytes)