Clipping; Stencil Test; Raster Operation - Samsung S3C2416 User Manual

S3C2416X RISC MICROPROCESSOR

4.3 CLIPPING

Clipping discards the pixels (after rotation) outside the clipping window. The discarded pixels will not go through
the rest of rendering pipelines.
Note that the clipping windows must reside totally inside the screen. Setting the clipping window the same size
with the screen will disable the clipping effect, and a clipping window bigger than the screen size is not allowed.
4.3.1 Related Registers
CW_LT_REG
CW_RB_REG

4.4 STENCIL TEST

The Stencil Test conditionally discards a pixel based on the outcome of a comparison between the color value of
this pixel of the source image and the DR(min)/DR(max) values. If each field (R, G, B, A) of the color value falls in
the range of [ DR(min), DR(max)], this pixel is passed to the next stage; otherwise, discarded. User can disable
the stencil test on a specific field by clearing the corresponding bits in COLORKEY_CNTL. Note that each field of
DR_MIN and DR_MAX is 8-bit wide, regardless of the source color mode setting.
4.4.1 Related Registers
COLORKEY_CNTL
COLORKEY_DR_MIN
COLORKEY_DR_MAX

4.5 RASTER OPERATION

Raster Operation performs Boolean operations on three operands: source, destination and third operand
according to the 8-bit ROP value specified by the user. The truth table of ROP is given in the following table.
Coordinate of the leftmost topmost point of the clipping window
Coordinate of the rightmost bottommost point of the clipping window
Stencil Test configurations, such as enable/disable the test and so on.
Set the DR(min) value for each field
Set the DR(max) value for each field
Source Destination
0 0
0 0
0 1
0 1
1 0
1 0
1 1
1 1
Third Operand ROP Value
0
1
0
1
0
1
0
1
Bit0
Bit1
Bit2
Bit3
Bit4
Bit5
Bit6
Bit7
2D
18-11