CL-PS7500FE View Datasheet(PDF) - Cirrus Logic

Part Name

Description

Manufacturer

CL-PS7500FE

System-on-a Chip for Internet Appliance

Cirrus Logic 

CL-PS7500FE

System-on-a-Chip for Internet Appliance

q The value of d is arranged with the decimal point between d23 and d22, and is normalized so that for an ordi-

nary number 1 ≤ d23 ≤ 9.

q The guaranteed ranges for d and e are 21 and 4 digits respectively: e6, e5, e4 and d2, d1, d0 may always be

zero in a particular system.

q The result is undefined if any of the packed digits is hexadecimal A through F.

Expanded Packed Decimal Values

Table 18-4. Expanded Packed Decimal Values

Sign

Sign

Exponent Digit values

(top bit) (next bit)

Quiet NaN

x

x

FFFFFFF d23 > 7, rest non-zero

Signalling NaN x

x

FFFFFFF d23 < 8, rest non-zero

+/- Infinity

0,1

x

FFFFFFF all 0

+/- Zero

0,1

0

0000000 all 0

Number

0,1

0,1

0-9999999 1-9.99999999999999999999999

All other combinations are undefined.

18.4 The Floating-Point Status Register (FPSR)

The floating-point status register (FPSR) consists of:

q a system ID byte

q an exception trap enable byte

q a system control byte

q a cumulative exception flags byte

NOTE: The FPSR is not cleared on reset. It is typically cleared by the support code using an appropriate WFS.

18.4.1 System ID Byte

31

24

0

SysId

The 8-bit SysId allows a user or operating system to distinguish which floating-point system is in use. The

top bit (bit 31) is:

set

clear

for HARDWARE (i.e. fast) systems

for SOFTWARE (i.e. slow) systems

NOTE: The SysId is read-only.

164

FLOATING-POINT COPROCESSOR PROGRAMMER’S

MODEL

ADVANCE DATA BOOK v2.0

June 1997

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