ST20-C1 STMICROELECTRONICS [STMicroelectronics], ST20-C1 Datasheet - Page 101

• Manufacturer Part Number: ST20-C1
• Description: Instruction Set Reference Manual
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

dequeue
Code: 23 F8
Description: Load into Breg a pointer to the first process from the queue control
block pointed to by Areg. Load into Areg a boolean value indicating whether a
process was found. The queue control block is defined in Chapter 7.
Definition:
Status Register:
Comments:
See also: enqueue run
if (frontptr = NotProcess)
{
}
else
{
}
Creg
where frontptr = word[Areg @ q.FPtrLoc]
No effect
Secondary instruction.
This instruction may require 4 memory accesses. If the queue structure is in off-
chip memory then interrupt latency may be affected.
Areg must be word aligned (i.e. divisible by 4).
Chapter 7.
Areg
Breg
Areg
Breg
if (frontptr = backptr)
else
word [Areg @ q.FPtrLoc]
word [Areg @ q.FPtrLoc]
backptr = word[Areg @ q.BPtrLoc]
undefined
false
undefined
true
frontptr
NotProcess
word[ frontptr @ pw.Link ]
8 Instruction Set Reference
dequeue a process
--
--
--
--
queue is empty
queue is not empty
one process on queue
many processes on queue
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