MC68030 Datasheet, PDF (401/602 Pages) Motorola, Inc – ENHANCED 32-BIT MICROPROCESSOR

Coprocessor Interface Description
15 14 13 12 11 10
9
8
7
6
5
4
3
2
1
0
CA PC 0
0
0
1
1
1
0
0
0
0
0
0
0
0
Figure 10-26. Transfer Operation Word Primitive Format
This primitive uses the CA and PC bits as previously described. If this primitive is issued with
CA=0 during a conditional category instruction, the main processor initiates protocol
violation exception processing.
When the main processor reads this primitive from the response CIR, it transfers the F-line
operation word of the currently executing coprocessor instruction to the operation word CIR.
The value of the scanPC is not affected by this primitive.
10.4.7 Transfer from Instruction Stream Primitive
The transfer from instruction stream primitive initiates transfers of operands from the
instruction stream to the coprocessor. This primitive applies to general and conditional
category instructions. Figure 10-27 shows the format of the transfer from instruction stream
primitive.
15
14 13 12 11 10
9
CA
PC
0
0
1
1
1
8
7
1
0
LENGTH
Figure 10-27. Transfer from Instruction Stream Primitive Format
This primitive uses the CA and PC bits as previously described. If this primitive is issued with
CA=0 during a conditional category instruction, the main processor initiates protocol
violation exception processing.
Bits [0-7] of the primitive format specify the length, in bytes, of the operand to be transferred
from the instruction stream to the coprocessor. The length must be an even number of bytes.
If an odd length is specified, the main processor initiates protocol violation exception
processing (refer to 10.5.2.1 Protocol Violations).
This primitive transfers coprocessor-defined extension words to the coprocessor. When the
main processor reads this primitive from the response CIR, it copies the number of bytes
indicated by the length field from the instruction stream to the operand CIR. The first word
or long word transferred is at the location pointed to by the scanPC when the primitive is
read by the main processor, and the scanPC is incremented after each word or long word
is transferred. When execution of the primitive has completed, the scanPC has been
incremented by the total number of bytes transferred and points to the word following the
last word transferred. The main processor transfers the operands from the instruction
stream using a sequence of long-word writes to the operand CIR. If the length field is not an
even multiple of four bytes, the last two bytes from the instruction stream are transferred
using a word write to the operand CIR.
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MC68030 USER’S MANUAL
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