ST20-C1 STMICROELECTRONICS [STMicroelectronics], ST20-C1 Datasheet - Page 153

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

stop
Code: 23 F4
Description: Terminate the current process, saving the current Iptr and Wptr for later
use, and start the next process from the scheduling queue. If the scheduling queue is
empty then the CPU will become idle. This instruction is implemented in two stages to
protect interrupt latency. The first stage deschedules the current process and sets the
start_next_task status bit. The second stage clears the start_next_task status bit
and starts the next process. An interrupt may occur between the two stages.
Definition:
if ( stop trap handler installed )
else
{
take stop trap
word [Tdesc @ pw.Iptr]
word [Tdesc @ pw.Wptr]
Status
Status
Status
Status
Status
Status
Status
Status
-- start next process on scheduling queue
if (frontptr = NotProcess)
{
}
else
{
Status
Status
if ( idle trap handler installed )
else
Status
Status
Tdesc
Wptr
local_interrupt_enable
overflow
undeflo w
carry
interrupt_mode
trap_mode
start_next_task
timeslice_count
take idle trap
set idle
sleep
user_mode
sleep
user_mode
clear
set
frontptr
word [frontptr @ pw.Wptr]
next instruction
Wptr
set
clear
clear
clear
clear
clear
clear
MaxTimesliceCount
set
clear
-- queue is empty, so become idle
-- processes waiting, so start next process
8 Instruction Set Reference
stop process
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