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Programming Model
TVP4020
Programmers Reference Manual
14
address-tag with Count=n-1, Mode=0
value 1
...
value n
This is commonly used for image download by setting the
SyncOnHostData bit in the Render command.. In this format the 32-bit
tag description contains a tag value and a count specifying the number
of data words following in the buffer. The DMA controller writes each of
the data words to the same address tag. For example, this is useful for
image download where pixel data is continuously written to the Color
register. The bottom 9 bits specify the register to which the data should
be written; the high-order 16 bits specify the number of data words
(minus 1) which follow in the buffer and which should be written to the
address tag (note that the 2-bit mode field for this format is zero so a
given tag value can simply be loaded into the low order 16 bits).
A special case of this format is where the top 16 bits are zero indicating
that a single data value follows the tag (
i.e. the 32-bit tag description is
simply the address tag value itself). This allows simple DMA buffers to
be constructed which consist of tag/data pairs. For example to render a
horizontal span 10 pixels long starting from (2,5) the DMA buffer could
look like this:
StartXDom
2 << 16
StartY
5 << 16
StartXSub12 << 16
Count
1
Render
(trapezoid render command)
Increment Format
address-tag with Count=n-1, Mode=1
value 1
...
value n
This format is similar to the hold format except that as each data value is
loaded the address tag is incremented (the value in the DMA buffer is
not changed; P
ERMEDIA
updates an internal copy). Thus, this mode
allows contiguous P
ERMEDIA
registers to be loaded by specifying a single
32-bit tag value followed by a data word for each register. The low-order
9 bits specify the address tag of the first register to be loaded. The 2 bit
mode field is set to 1 and the high-order 16 bits are set to the count
Summary of Contents for TVP4020 PERMEDIA 2
Page 1: ...Texas Instruments TVP4020 PERMEDIA 2 Programmer s Reference Manual Issue 4 ...
Page 284: ...TVP4020 Programmers Reference Manual A Gouraud Shaded Triangle 275 ...
Page 292: ...TVP4020 Programmers Reference Manual Register Tables 283 ...
Page 314: ...TVP4020 Programmers Reference Manual Index 305 ...
Page 315: ...Index TVP4020 Programmers Reference Manual 306 Index ...
Page 323: ...Index TVP4020 Programmers Reference Manual 314 ...