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# PCB
PCB information
## context
Contains context infromation for the curernt process.
- memory context (pcb->memctx)
- stores page directory and vitural address allocateor (see MEMORY.md)
- context save area (pcb->regs)
## medatada
- `pid` - process idenfitication number
- `parent` ` - parent of the current process
- can be NULL if the init process
- `state` - the current runing state of the process
- `UNUSED` - proces in ptable is not used
- `NEW` - process in ptable has been allocated but has not been initalized
- `READY` - process is ready to be dispatched (and in ready queue)
- `RUNNING` - process is the current running process (and in no queues)
- `BLOCKED` - process is in a syscall queue waiting on their syscall to return
- `ZOMBIE` - process is a zombie and waiting to be cleaned up (in zombie queue)
- `priority` - running process priority
- any number form 0 to SIZET_MAX
- higher priority means longer wait to be scheduled
- `ticks` - number of ticks the process has been running for
- set to zero when process is not running
## heap
- `heap_start` is the start of the progams heap
- `heap_len` is the length of the programs heap
## open files
- `open_files` is a list of currently opened files indexed by file descriptor
## elf metadata
- `elf_header` - the programs elf header (Elf64_Ehdr)
- `elf_segments` - the programs loadable elf segments (Elf64_Phdr[])
- `n_elf_segments` - the number of elf segmsnts the program has
## queue linkage
- `next` - the next pcb in the current queue this pcb is in
## processs state information
- `syscall` - the current syscall this process is blocked on
- `wakeup` - the number of ticks until the process can be waked up (used during SYS_sleep)
- `exit_status` - the exit status of the process when a zombie
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