Blkdestwidth – Cirrus Logic EP93xx User Manual
Page 291
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Copyright 2007 Cirrus Logic
Graphics Accelerator
EP93xx User’s Guide
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The value in this field specifies the number of 32 bit words,
minus 1, that are needed to contain all of the pixels that
comprise width of the display. The value of LEN is
determined by:
1) Find how many pixels occupy a 32-bit word. For
example, four 8-bit pixels can occupy a 32-bit word.
2) Find the width of the display in pixels. For example, a
640x480 display has a width of 640 pixels.
3) The line length, LEN, is determined by the stride of the
display, that is, how many 32-bit words are needed to
populate the width of the display with pixels. From steps 1
and 2, the stride for this example is 640 pixels divided by
4, where 4 is the number of 8-bit pixels that occupy a
word. So, for this example, LEN = 640 / 4 = 160 = 0xA0.
Usually the same LEN value is used in both the
register.
BLKDESTWIDTH
Address:
0x8004_0018 - Read/Write
Default:
0x0000_0000
Mask:
0x0000_0FFF
Definition:
Block Function Destination Width Register.
Bit Descriptions:
RSVD:
Reserved - Unknown during read
WIDTH:
Width - Read/ Write
For Block Fill and Block Copy functions, the value in this
field specifies the number of 32-bit words, minus 1, that
are needed to contain the pixels in the 1st scan line of the
destination image. For example, please refer to the note in
. The maximum value for the
field is 0xFFE = 4095 words.
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
RSVD
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
RSVD
WIDTH