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All task switches will occur after the current instructions in the queue have finished being processed and written
Will not conflict with other writes within the same instruction queue
Triggers `illegal instruction` exception if multiple task switches occur within the same instruction queue
TODO: mark current CPU executing it
Call process:
Only allowed to be used by the original process
Triggers `invalid operation` exception otherwise
Custom ID must match between the tdt at the index and the one specified by the instruction, and the target must be marked as valid
Sets the `zero` flag and skips execution of this instruction otherwise
One segment may be passed to the callee, used by the callee with all segment bits set
Caller may call with all segment bits set to not pass a segment
Current process id in the tdt will be set to the id of the callee
Current segments will be saved to the tdt, and those of the callee will be loaded
PR as specified in the callee's tdt for the callable segment will be loaded, and current PR is saved to the tdt
IP of next instruction is saved to tdt
Stack pointers are saved to tdt
Jumps to <callee's callable segment>, offset 0
Return process:
Only allowed to be used by the callee
Triggers `invalid operation` exception otherwise
Segments will be loaded from the tdt
Process id in the tdt is set to the original process's id
Stack pointers are loaded from the tdt
PR is loaded from the tdt
IP is loaded from the tdt
Switch process:
Only allowed to be used by the original process
Triggers `invalid operation` exception otherwise
Only allowed to switch to a process that is not currently active
Sets the `zero` flag and skips execution of this instruction otherwise
Custom ID must match between the tdt at the index and the one specified by the instruction, and the target must be marked as valid
Sets the `zero` flag and skips execution of this instruction otherwise
All registers are saved to the current tdt and loaded from the target's tdt index
Loads all registers from the target's tdt index
Switch process and exit exception/interrupt handler:
Only allowed to be used while in an exception/interrupt handler
Triggers `invalid operation` exception otherwise
Only allowed to switch to a process that is not currently active
Sets the `zero` flag and skips execution of this instruction otherwise
Custom ID must match between the tdt at the index and the one specified by the instruction, and the target must be marked as valid
Sets the `zero` flag and skips execution of this instruction otherwise
All registers are saved to the current tdt and loaded from the target's tdt index
IP and PR are saved as if all exception/interrupt handlers returned
This saving step will be skipped if the entry for the current process is not flagged as valid
Allows more interrupts to be processed
Loads all registers from the target's tdt index
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