Color Map Sharing |
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Like the CRX-24Z, the CRX-48Z has five separate hardware color
maps (one for overlay, four for image planes). However, on the CRX-48Z
the four image plane color maps may be used for CMAP_NORMAL, CMAP_MONOTONIC, or CMAP_FULL, with no restriction.
( The CRX-24Z has four image plane color maps, but only one can
be used for 12 or 24 bit CMAP_FULL,
the other three are used for CMAP_NORMAL
and/or CMAP_MONOTONIC).
Color map allocation is managed by the X Server, and on the CRX-48Z,
the four color maps are used in an optimal fashion such that color
map "thrashing" (if more than four color maps are needed) is greatly
reduced. The CRX-48Z does not use the SB_X_SHARED_CMAP
environment variable, or the 6|6|6 color map mode
(as sometimes used by the CRX device).
Echos on CRX-24Z are rendered to the overlay planes. On the
CRX-48Z device, echos are rendered in a set of planes separate from
the overlay or image planes, and you may notice slight behavioral
differences between echos on the two devices. Under most circumstances
these differences will pose no problems. For details on device dependent
echo information, see the chapter for your device in in this manual.
On devices with overlay planes, a common operation may be
to have a window in the image planes with a transparent child window
in the overlay planes. In this case, the Starbase entry point inquire_capabilities should
be used. If the IC_TRANS_WIN_IMAGE_CURSOR
bit is set, the echo should be associated with the fildes for the image plane
window. If this bit is not set, the echo should be associated with
the fildes for
the overlay plane window. (The bit will be
set for the CRX-48Z device, but may not be on other devices.)
The CRX-24Z has 24 image planes and 8 overlay planes. The
24 image planes on the CRX-24Z are organized as three banks of 8
planes each. If an 8-bit window is opened in the image planes, then
the Starbase bank_switch
function is used to select bank 0 or 1 for block operations such
as block_read,
block_write,
and block_move.
If a 24-bit window is opened, then the bank_switch
function is used to select bank 0, 1, or 2 for block operations.
The CRX-48Z has 48 image planes and 8 overlay planes. The
48 image planes are organized as six banks of 8 planes each. If
an 8-bit window is opened in the image planes, then bank_switch is used to select
bank 0 or 1, just as on the CRX-24Z. If a 24-bit window is opened,
then bank_switch
is used to select bank 0, 1, 2, 3, 4, or 5. For details on how these
banks are organized refer to the "hpcrx48z Device Driver" chapter
in this manual.
There are very few source incompatibilities between the CRX-24Z
and the CRX-48Z devices. CRX-24Z only supports fill_pattern up to
4x4 patterns. CRX-48Z supports fill_pattern sizes up to 4x4.
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