Table 2-1. Pipeline Flow For Concurrent Operations - Lucent Technologies DSP1617 Information Manual

Information Manual
April 1998
2.1 Device Architecture Overview
2.1.2 Concurrent Operations (continued)
Table 2-1 shows the sequence of instructions whose operations are described in the previous example. The pipe-
lining of functional operations and data transfers is illustrated. The interpretation of the instructions is as follows:
y = Y means place the contents of memory space Y in register y. In the actual instruction, Y could be replaced by
*rM++. *rM++ denotes the memory location pointed to by the address in register rM (M = <0—3>) and postincre-
ment the address. Similarly, x = X means place the contents of memory space X in register x. In the actual
instruction, X could be replaced by *pt++. *pt++ denotes the memory location pointed to by the address in the pt
register and postincrement the address. p = x * y means multiply the data in registers x and y and put the result in
register p. a0 = a0 + p means add the value in p to the previous value in accumulator a0. The subscripts are
attached to indicate the order of the operation and to demonstrate the flow of the results of operations on y and x.
In this example, an accumulation takes place during every instruction cycle but there is a delay of three instructions
from the data into the x and y registers to the final accumulation.

Table 2-1. Pipeline Flow for Concurrent Operations

Instruction #
(1)
(2)
(3)
The most efficient programs use the parallelism as described above to the fullest extent. The instructions that
allow concurrent operations are the multiply/ALU instructions with their associated data transfers and are described
in detail in Chapter 4, Instruction
Lucent Technologies Inc.
DSP1611/17/18/27/28/29 DIGITAL SIGNAL PROCESSOR
(continued)
Accumulator
a0 = a0 + p p
0 –1 0
a0 = a0 + p p
1 0 1
a0 = a0 + p p
2 1 2
Set.
DRAFT COPY
Multiplier Registers
= x * y y = Y
1 1 1 2
= x * y y = Y
2 2 2 3
= x * y y = Y
3 3 3 4
Hardware Architecture
, x = X
2 2 2
, x = X
3 3 3
, x = X
4 4 4
2-3