6-34
Video Interface and On-Screen Display
Final Rev F
Copyright 1996 by LSI Logic Corporation. All rights reserved.
In non-linked list mode, the total number of pixels in an OSD region
is not a multiple of 32 pixels (2-bpp mode) or 16 pixels (4-bpp mode)
The number of bits in the bitmap exceeds the available memory
space.
The color programmed into the color register is not a legal CCIR 601
color
The number of pixels requested on each scan line exceeds imple-
mentation limits
The total OSD area exceeds implementation limits
6.9.11
OSD
Compatibility
Mode
If the OSDMD bit in Group 6, Register 28, is clear, the OSD operates in
a mode similar to the SGS-Thomson ST3220 controller (no linked lists).
If set, linked lists are enabled.
No Linked List Mode – In this mode of operation, the DRAM stores
eld 1 of each OSD consecutively, one following the other. Also, the
DRAM stores eld 2 of each OSD consecutively. The L64005 stores the
address for eld 1 of the rst OSD in the Group 6, Index 24 and 25, OSD
Field Pointer 1 Registers, in 32-byte resolution. Similarly, the L64005
stores the address for eld 2 of the rst OSD in the Group 6, Index 26
and 27 OSD Field Pointer 2 Registers, in 32-byte resolution. In this mode
of operation, the OSD address bits, OSDA[17:0], are not used and
should be cleared. The bitmap data of any OSD is followed by the header
of the next OSD. A terminating header needs to be appended after the
data corresponding to the last OSD. This header can either correspond
to the header of the rst OSD or contain parameters that are out of the
range of the OSD.
Linked List Mode – In this mode of operation, the DRAM may not store
eld 1 of each OSD and eld 2 of each OSD consecutively. Instead, the
OSD address bits, OSDA[17:0], in the header of each OSD eld point to
the DRAM location of the corresponding eld of the next OSD. The
OSDA[17:0] bits of the next OSD eld point to the DRAM location of the
following OSD eld, and so on. The OSDA[17:0] bits of the last OSD in
the list can point either to the DRAM location of the rst OSD in the list
or to an address that is out of the range of the allocated OSD area.The
L64005 stores the address for eld 1 of the rst OSD in the Group 6,
Index 24 and 25, OSD Field Pointer 1 Registers, in 32-byte resolution.
Similarly, the L64005 stores the address for eld 2 of the rst OSD in the