Intel 815 manual BLT Engine Instruction Definitions, 12.3.1. BR00-BLT Opcode and Control

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

Clip

Setup

Instruction Target (Opcode)

Reserved.

Monochrome

Bit (0) /

SY

Inst

Mono

Must be

Source Start

Byte (1)

Pattern

Zero

Packed

15

14

13

12

11

10

8

7

5

4

3

2

1

0

Reserved.

Text

Scan

Pixel

Destination

Pattern

DST

Color

Mono

Color

Mono

Must be

BLT

Line

BLT

Transparency

Vertical

RMW

Source

Source

Pattern

Pattern

Zero

BLT

Mode

Alignment

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.

184