Figure 4-2.Direct Data Addressing - Lucent Technologies DSP1617 Information Manual

DSP1611/17/18/27/28/29 DIGITAL SIGNAL PROCESSOR
Instruction Set
4.3 Addressing Modes
4.3.3 Direct Data Addressing (continued)
INSTRUCTION
IN X-MEMORY
SPACE
ybase
REGISTER
IN YAAU
Example of *(OFFSET) = DR
a0=0xface
ybase=0x1232
*(0x15)=a0
4-8
(continued)
15 11 10
T-FIELD
R/W
16
XDB
16
CONTROL
15
BASE
11
YAB
16
RAM
Figure 4-2. Direct Data Addressing
/* Initialize value in accumulator.
/* Store the upper 11 bits of 0x1232 into ybase as follows: */
/* Place (0001 0010 001) into the upper 11 bits of ybase
/* Offset=0x15; Store (1 0101) into lower 5 bits of ybase
/* Address in ybase is 0x1215, demonstrated below:
/* 0001 0010 001
/*
/* 0001 0010 0011 0101
/* Store 0xface (contents of a0) into location 0x1235.
DRAFT COPY
9 6 5 4
DR SPECIFIED
1
5
5 4
5
YDB
16
1 0101
Information Manual
0
OFFSET
DR = *(OFFSET)
or
*(OFFSET) = DR
OFFSET
5
0
REGISTER DR
= upper 11 bits
= lower 5 bits
= address=0x1235
Lucent Technologies Inc.
April 1998
5-4149
*/
*/
*/
*/
*/
*/
*/
*/