User's Manual

Intel® 815 Chipset: Graphics Controller PRM, Rev 1.0
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12.3. BLT Engine Instruction Definitions
This section describes the BLT Engine instruction fields. These descriptions are in the format of register
descriptions. For debug purposes, the read-only addresses indicated provide BLT Engine status.
12.3.1. BR00—BLT Opcode and Control
Memory Offset Address: 40000h
Default: 0000 0000
Attributes: RO; DWord accessible
BR00 is the last executed instruction DWord 0. Bits [22:5] are written by every DW0 of every
instruction. Bits [31:30] and [4:0] are status bits. Bits [28:27] are written from the DW0 [15:14] of a
Setup instruction and Bit 29 is written with a 1 when a Setup instruction is written. Bit 29 is a decode of
the Setup instruction Opcode.
31 30 29 28 22 21 20 19 17 16
BLTB
SY
Clip
Inst
Setup
Mono
Pattern
Instruction Target (Opcode) Reserved.
Must be
Zero
Monochrome
Source Start
Bit (0) /
Byte (1)
Packed
15 14 13 12 11 10 8 7 5 4 3 2 1 0
Reserved.
Must be
Zero
Text
BLT
Scan
Line
BLT
Pixel
BLT
Destination
Transparency
Mode
Pattern
Vertical
Alignment
DST
RMW
Color
Source
Mono
Source
Color
Pattern
Mono
Pattern
Bit Descriptions
31 BLT Engine Busy. This bit indicates whether the BLT Engine is busy (1) or idle (0). This bit is
replicated in the SETUP BLT Opcode & Control register.
1 = Busy
0 = Idle
30 Clip Instruction. The current instruction performs clipping (1).
29 Setup Monochrome Pattern. This bit is decoded from the Setup instruction opcode to identify
whether a color (0) or monochrome (1) pattern is used with the SCANLINE_BLT instruction.
1 = Monochrome
0 = Color
28:22 Instruction Target (Opcode). This is the contents of the Instruction Target field from the last BLT
instruction. This field is used by the BLT Engine state machine to identify the BLT instruction it is to
perform. The opcode specifies whether the source and pattern operands are color or monochrome.
21:20 Reserved. Must be Zero.
19:17 Monochrome Source Start. This field indicates the starting monochrome pixel bit position within a
byte per scan line of the source operand. The monochrome source is word aligned which means that
at the end of the scan line all bits should be discarded until the next word boundary.
16 Bit/Byte Packed . Byte packed is for the Windows* NT* driver
0 = Bit
1 = Byte
15:14 Reserved. Must be Zero.