BIOS functions
[Bios Calls]

Reset functions
void	SoftReset (void)
void	RegisterRamReset (u32 flags)
Halt functions
void	Halt (void)
void	Stop (void)
void	IntrWait (u32 flagClear, u32 irq)
void	VBlankIntrWait (void)
	Wait for the next VBlank (swi 05h).
Math functions
s32	Div (s32 num, s32 den)
	Basic integer division (swi 06h).
s32	DivArm (s32 den, s32 num)
	Basic integer division, but with switched arguments (swi 07h).
u32	Sqrt (u32 num)
	Integer Square root (swi 08h).
s16	ArcTan (s16 dydx)
	Arctangent of dydx (swi 08h).
s16	ArcTan2 (s16 x, s16 y)
	Arctangent of a coordinate pair (swi 09h).
Memory copiers/fillers
void	CpuSet (const void *src, void *dst, u32 mode)
	Transfer via CPU in (half)word chunks.
void	CpuFastSet (const void *src, void *dst, u32 mode)
	A fast transfer via CPU in 32 byte chunks.
Rot/scale functions
void	ObjAffineSet (const ObjAffineSource *src, void *dst, s32 num, s32 offset)
	Sets up a simple scale-then-rotate affine transformation (swi 0Eh).
void	BgAffineSet (const BgAffineSource *src, BgAffineDest *dst, s32 num)
	Sets up a simple scale-then-rotate affine transformation (swi 0Eh).
Decompression (see GBATek for format details)
void	BitUnPack (const void *src, void *dst, const BUP *bup)
void	LZ77UnCompWram (const void *src, void *dst)
void	LZ77UnCompVram (const void *src, void *dst)
void	HuffUnComp (const void *src, void *dst)
void	RLUnCompWram (const void *src, void *dst)
void	RLUnCompVram (const void *src, void *dst)
void	Diff8bitUnFilterWram (const void *src, void *dst)
void	Diff8bitUnFilterVram (const void *src, void *dst)
void	Diff16bitUnFilter (const void *src, void *dst)
Sound Functions
void	SoundBias (u32 bias)
void	SoundDriverInit (void *src)
void	SoundDriverMode (u32 mode)
void	SoundDriverMain (void)
void	SoundDriverVSync (void)
void	SoundChannelClear (void)
u32	MidiKey2Freq (void *wa, u8 mk, u8 fp)
void	SoundDriverVSyncOff (void)
void	SoundDriverVSyncOn (void)
Multiboot handshake
int	MultiBoot (MultiBootParam *mb, u32 mode)
Functions
u32	BiosCheckSum (void)

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Function Documentation

s16 ArcTan

(

s16

dydx

)

Arctangent of dydx (swi 08h).

Parameters:

dydx

Slope to get the arctangent of.

Returns:

Arctangent of dydx in the range <-4000h, 4000h>, corresponding to <-½π, ½π> .

Note:

Said to be inaccurate near the range's limits.

s16 ArcTan2	(	s16	x,
		s16	y
	)

Arctangent of a coordinate pair (swi 09h).

This is the full-circle arctan, with an angle range of [0,FFFFh].

void BgAffineSet	(	const BgAffineSource *	src,
		BgAffineDest *	dst,
		s32	num
	)

Sets up a simple scale-then-rotate affine transformation (swi 0Eh).

Uses a single ObjAffineSource struct to set up an array of affine matrices (either BG or Object) with a certain transformation. The matrix created is

sx·cos(α)	-sx·sin(α)
sy·sin(α)	sy·cos(α)

Parameters:

	src	Array with scale and angle information.
	dst	Array of affine matrices, starting at a pa element.
	num	Number of matrices to set.
	offset	Offset between affine elements. Use 2 for BG and 8 for object matrices.

Note:

Each element in src needs to be word aligned, which devkitPro doesn't do anymore by itself.

void CpuFastSet	(	const void *	src,
		void *	dst,
		u32	mode
	)

A fast transfer via CPU in 32 byte chunks.

This uses ARM's ldmia/stmia instructions to copy 8 words at a time, making it rival DMA transfers in speed. With bit 26 set it will keep the source address constant, effectively performing fills instead of copies.

Parameters:

	src	Source address.
	dst	Destination address.
	mode	Number of words to transfer, and mode bits.

Note:

Both source and destination must be word aligned; the number of copies must be a multiple of 8.

In fill-mode (bit 26), the source is still an address, not a value.

memcpy32/16 and memset32/16 basically do the same things, but safer. Use those instead.

void CpuSet	(	const void *	src,
		void *	dst,
		u32	mode
	)

Transfer via CPU in (half)word chunks.

The default mode is 16bit copies. With bit 24 set, it copies words; with bit 26 set it will keep the source address constant, effectively performing fills instead of copies.

Parameters:

	src	Source address.
	dst	Destination address.
	mode	Number of transfers, and mode bits.

Note:

This basically does a straightforward loop-copy, and is not particularly fast.

In fill-mode (bit 26), the source is still an address, not a value.

s32 Div	(	s32	num,
		s32	den
	)

Basic integer division (swi 06h).

Parameters:

	num	Numerator.
	den	Denominator.

Returns:

num / den

Note:

div/0 results in an infinite loop. Try DivSafe instead

s32 DivArm	(	s32	den,
		s32	num
	)

Basic integer division, but with switched arguments (swi 07h).

Parameters:

	num	Numerator.
	den	Denominator.

Returns:

num / den

Note:

div/0 results in an infinite loop.

void ObjAffineSet	(	const ObjAffineSource *	src,
		void *	dst,
		s32	num,
		s32	offset
	)

Sets up a simple scale-then-rotate affine transformation (swi 0Eh).

Uses a single ObjAffineSource struct to set up an array of affine matrices (either BG or Object) with a certain transformation. The matrix created is

sx·cos(α)	-sx·sin(α)
sy·sin(α)	sy·cos(α)

Parameters:

	src	Array with scale and angle information.
	dst	Array of affine matrices, starting at a pa element.
	num	Number of matrices to set.
	offset	Offset between affine elements. Use 2 for BG and 8 for object matrices.

Note:

Each element in src needs to be word aligned, which devkitPro doesn't do anymore by itself.

void VBlankIntrWait

(

void

)

Wait for the next VBlank (swi 05h).

Note:

Requires clearing of REG_IFBIOS bit 0 at the interrupt tonc's master interrupt handler does this for you.

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