376 datasheet(86/95 Pages) INTEL

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376 EMBEDDED PROCESSOR

Table 81 80376 Instruction Set Clock Count Summary

(Continued)

Clock

Number

Instruction

Format

Counts

of Data

Notes

Cycles

PROTECTION CONTROL

(Continued)

SMSW e Store Machine

Status Word

00001111

00000001

mod100

r m

2 2

a c

STR e

Store Task Register

To RegisterMemory

00001111

00000000

mod001

r m

2 2

VERR e Verify Read Accesss

RegisterMemory

00001111

00000000

mod100

r m

1011

acip

VERW e Verify Write Accesss

00001111

00000000

mod101

r m

1516

acip

NOTES

a Exception 13 fault (general violation) will occur if the memory operand in CS DS ES FS or GS cannot be used due to

either a segment limit violation or access rights violation If a stack limit is violated and exception 12 (stack segment limit

violation or not present) occurs

b For segment load operations the CPL RPL and DPL must agree with the privilege rules to avoid an exception 13 fault

(general protection violation) The segments’s descriptor must indicate ‘‘present’’ or exception 11 (CS DS ES FS GS not

present) If the SS register is loaded and a stack segment not present is detected an exception 12 (stack segment limit

violation or not present occurs)

c All segment descriptor accesses in the GDT or LDT made by this instruction will automatically assert LOCK to maintain

descriptor integrity in multiprocessor systems

d JMP CALL INT RET and IRET instructions referring to another code segment will cause an exception 13 (general

protection violation) if an applicable privilege rule is volated

e An exception 13 fault occurs if CPL is greater than 0

f An exception 13 fault occurs if CPL is greater than IOPL

g The IF bit of the flag register is not updated if CPL is greater than IOPL The IOPL field of the flag register is updated only

if CPL e 0

h Any violation of privelege rules as applied to the selector operand does not cause a protection exception rather the zero

flag is cleared

i If the coprocessor’s memory operand violates a segment limit or segment access rights an exception 13 fault (general

protection exception) will occur before the ESC instruction is executed An exception 12 fault (stack segment limit violation

or no present) will occur if the stack limit is violated by the operand’s starting address

j The destination of a JMP CALL INT RET or IRET must be in the defined limit of a code segment or an exception 13 fault

(general protection violation) will occur

k If CPL s IOPL

l If CPL l IOPL

m LOCK is automatically asserted regardless of the presence or absence of the LOCK prefix

n The 80376 uses an early-out multiply algorithm The actual number of clocks depends on the position of the most signifi-

cant bit in the operand (multiplier) Clock counts given are minimum to maximum To calculate actual clocks use the follow-

ing formula

Actual Clock e if m kl 0 then max ( log2

lml 3) a 9 clocks

if m e 0 then 12 clocks (where m is the multiplier)

o An exception may occur depending on the value of the operand

p LOCK is asserted during descriptor table accesses

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