Cirrus-logic EP93xx Manual de usuario descargar pdf (Pagina 267)

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DS785UM1 8-3

Graphics Accelerator

EP93xx User’s Guide

2. Logical Destination

3. Transparency

8.2.2 Remapping

The Graphics Accelerator supports single bit pixel remapping with foreground/background or

foreground/transparency to system color depth images (1 bpp mapped to 4, 8, 16 or 24 bpp

expansion.) Images stored as a single bit plane can be expanded with a foreground color and

either transparent or background color. Remapping can be used for fast transfer of text,

single color patterns, and single color bit maps to video memory.

Note:The Graphics Accelerator only supports movement in the positive direction for X and Y. In

other words, use the remapping function only from the display top to bottom and from the

display left to right.

8.2.3 Block Fills

The Graphics Accelerator supports pixel addressed Block Fills and Block Copies with 4, 8,

16, or 24 bpp resolution. During Block Fills, rectangular blocks of pixels are replaced with the

pixel value that is in the “BLOCKMASK” register. For unpacked 24 bpp fills, the high byte is

set to 0x00.

8.2.4 Packed Memory Transfer

A packed source means that all bits in a word are used for the source image. The only

exception is the last word, which is not required to be used if the image size does not require

the storage. A packed source DOES NOT mean that all words are packed together. The lines

may have none, or one or more word(s) between each line. A line is defined as a continuous

block of words that contains pixel data.

In packed mode, the source can have a different layout than the destination. This is different

from non-packed mode where the “BLKSRCWIDTH” and “BLKDESTHEIGHT” are the same.

To enable a Packed Source transfer set the PACKD bit in the “BLOCKCTRL” register.

8.3 Line Draws

The Graphics Engine supports two types of hardware accelerated lines draws:

1. Breshenham Line Draw, or

2. Pixel Step Line Draw

The only programming difference between the two line draw algorithms is how the line

increment registers are set. The lines may be drawn using solid lines or patterned lines.

Accelerated line draw makes it possible to draw a single pixel width line between any two

points with sub pixel accuracy.

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Cirrus-logic EP93xx Manual de usuario Pagina 267

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