These registers are responsible for controlling how framebuffer data can be DMA’d from the DS GPU, and also for configuring the upscaling matrix.

Registers #

The physical address can be calculated by subtracting 0xEB00000 from the virtual address.

Control #

There are two matrix units, one at +0x200 for vertical (Y) scaling, and the other one at +0x300 for horizontal (X) scaling.

VAddress	Name	Width	Description
0x1EC1xn00	KRN_WIDTH	4	Kernel width - 1 is written here, 1 <= width <= 8 This decides how many pixels are written each batch.
0x1EC1xn04	KRN_PATTERN_BITS	4	If the corresponding bit for the current batch iteration index is set then a new pixel is read. The amount of set bits determine how many pixels are read each batch. Any bit indexes past KRN_WIDTH are ignored. This value is 8 bits, but it has to be written with a 32bit write.
0x1EC1xn40	KRN_MTX	0xC0	int kerneldata[6][8]; - matrix data is written here, height is always 6

Bit(s)	Description
0	Enable bit
1	Enable vertical matrix
2	Enable horizontal matrix
4	???
5	???
8-9	Input pixel mode? 0 = 4byte color, 1 = 3byte color, 2 = 2byte color, 3 = 2byte color
10-11	Output framebuffer rotation: 0 = normal, 1 = 90° CW (right), 2 = 180° CW (upside down, not mirrored), 3 = 270° CW (left)
12	Output tiling for use with the GPU. When set, the output width and height must be a multiple of 8.
15	Start bit (setting this will eventually raise MTX interrupt 0)
16	Data still available flag (?)

Bit(s)	Description
0-8	Output framebuffer width - 1 is written here, 1 <= width <= 512
16-25	Output framebuffer height - 1 is written here, 1 <= height <= 512

Reading this register will return pending interrupts. Writing this register will acknowledge pending interrupts where the bits are set.

Bit(s)	Description
0	FIFO ready (signal to start DMA)
1	FIFO overrun(?) (occurs if DMA is too slow)
2	FIFO underrun(?) (occurs on VBlank)

Interrupt Enable for the above interrupts.