PXD20RM Datasheet, PDF (1184/1628 Pages) Freescale Semiconductor, Inc – PXD20 Microcontroller

State writes from CPU or Geometry Engine
Command Handler
Command stream fetch, vector data
Vector commands, state writes
Vector Graphics
Geometry Engine
Edges, state writes
Vector Graphics
Rasterizer
Spans with alpha, state writes
Pixel color and alpha
2D Unit
Color reads and writes
Memory Arbiter
Pixel coordinates and alpha
Gradient / Texturing
Texture fetches
Memory bus accesses
Figure 31-13. 2D+VG Architecture
31.6.6.1 Command Handler
The purpose of the Command Handler is to read command streams from memory and send them onwards
to the vector graphics Geometry Engine and other units. These streams can be used like display lists in 3D
graphics. The unit supports three data streams from which register addresses and data can be read in
various formats. Multiple streams can also be used to implement subroutines in the display list. In addition
the unit has a stream marker mechanism that can be used to extend an already executing command list and
to report progress status back to the CPU through memory writes. Finally the unit can perform conditional
register writes base on feedback information from the Geometry Engine. This can be used to perform
bounding box tests and hardware based tiling.
31.6.6.2 Geometry Engine
The vector graphics Geometry Engine performs geometry operations on primitives. Input primitives can
be lines or curves (cubic/quadratic) specified with absolute or relative coordinates in a user specified
coordinate system. Curves are first split into line segments according to a given accuracy goal. After this
the resulting line path can optionally be converted into a thick stroke with possibly rounded joins and caps.
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PXD20 Microcontroller Reference Manual, Rev. 1
Preliminary—Subject to Change Without Notice
Freescale Semiconductor