beautypg.com

4 single precision mode – Motorola DSP96002 User Manual

Page 801

background image

MOTOROLA

19

3.1

CHANGE TO THE PROGRAMMING MODEL (INTEGER MODE)

To support the integer mode, bit 25 of the status register now features a new integer mode
(IM) bit as shown in Figure 3.

When the IM bit is cleared (0) the integer mode is disabled. When the IM bit is set, the
processor is in integer mode. The IM bit is cleared during reset.

3.1.1

Switching Into Integer Mode

The correct sequence for switching from the floating-point mode to integer mode is:

ORI #2,mr ; set the IM bit in MR register

NOP ; pipeline delay

NOP ; pipeline delay

parallel integer operation

4 SINGLE PRECISION MODE

The efficiency of the data ALU register file has been improved with the definition of the
new single precision mode (SPM), where the user has access to two data ALU register
files: a 10 floating-point register file (d0.h..d9.h, d0.m..d9.m) and a 10 integer register file
(d0.l..d9.l). If the program uses only single-precision MOVE operations and floating-point

LF

*

I1

I0

FZ

MP

IM

*

31

30

29

28

27

26

25

24

Integer Mode

Multiply

Flush to Zero

Interrupt Mask

Reserved

Loop Flag

MR

*

R1

R0

SIOP

SOVF

SUNF SDZ

SINX

23

22

21

20

19

18

17

16

IER

UN

S

OP

CC

NAN

NAN

ERR

OVF

UNF

DZ

INX

15

14

13

12

11

10

9

8

ER

A

R

LR

I

N

Z

V

C

7

6

5

4

3

2

1

0

CCR

Reserved

Figure 3 - DSP96002 Programming Model