Dr = *(Offset - Lucent Technologies DSP1617 Information Manual

Information Manual
April 1998

DR = *(OFFSET)

(load register from direct address in Y-space memory)
(DR) ← (*(ybase + OFFSET))
The contents of register DR are replaced with the current contents of the Y-space memory location at address
ybase + OFFSET. The ybase register holds the base address used for direct addressing. It can be loaded with
any 16-bit value (see the R = IM16 instruction on
The OFFSET is a 5-bit direct address (OFFSET from the ybase register) and is specified in the opcode. The OFF-
SET can have any value from 0 to 31.
Note: The upper 11 bits of ybase are concatenated with the OFFSET to form the direct address. The lower five
bits of ybase are ignored.
For direct addressing, register DR can be any of the following:
Register DR Field
r0 0000
r1 0001
r2 0010
r3 0011
a0 0100
a0l 0101
a1 0110
a1l 0111
Writing the psw also writes the a0 and a1 guard bits. Writing to a0 or a1 will cause bits 35—32 (the guard bits) to
be loaded with copies of bit 31. If clearing of a0l, a1l, or yl is enabled in the auc register, writes to a0, a1, or y will
cause bits 15—0 of that register to be cleared.
Bit 15 14
Field
1 1
Lucent Technologies Inc.
DSP1611/17/18/27/28/29 DIGITAL SIGNAL PROCESSOR
page
Register DR Field
y 1000
yl 1001
p 1010
pl 1011
x 1100
pt 1101
pr 1110
psw 1111
13 12 11 10
1 1 0 1
Words: 1
Cycles: 2
Group: Data Move
Addressing: Indirect, Register, Direct
Flags affected: None
Interruptible: Yes
Cacheable: Yes
Format: 9a
DRAFT COPY
B-8).
9—6 5
DR 1
Instruction Set Summary
4—0
OFFSET
B-16