anton/riscemu
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

Syscalls: cleaned up formatting and added instructions for extensions

Browse Source
This commit is contained in:
Anton Lydike 2022-04-18 20:25:35 +02:00
parent 10a3c4201e
commit 204d2c9a5b
2 changed files with 16 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
docs/syscalls.md
View File

@ -45,3 +45,6 @@ Requires flag `--scall-fs` to be set to True
* `a0`: file descriptor to close
* `return in a0`: 0 if closed correctly or -1
# Extending these syscalls
You can implement your own syscall by adding its code to the `SYSCALLS` dict in the [riscemu/syscalls.py](./riscemu/syscalls.py) file, creating a mapping of a syscall code to a name, and then implementing that syscall name in the SyscallInterface class further down that same file. Each syscall method should have the same signature: `read(self, scall: Syscall)`. The `Syscall` object gives you access to the cpu, through which you can access registers and memory. You can look at the `read` or `write` syscalls for further examples.

21
riscemu/syscall.py
View File

@ -8,10 +8,9 @@ import sys
from dataclasses import dataclass
from typing import Dict, IO
from .helpers import *
if typing.TYPE_CHECKING:
from riscemu.CPU import UserModeCPU
from .colors import FMT_SYSCALL, FMT_NONE
from .types import Int32, CPU
from .types.exceptions import InvalidSyscallException
SYSCALLS = {
63: 'read',
@ -20,7 +19,13 @@ SYSCALLS = {
1024: 'open',
1025: 'close',
}
"""All available syscalls (mapped id->name)"""
"""
This dict contains a mapping for all available syscalls (code->name)
If you wish to add a syscall to the built-in system, you can extend this
dictionary and implement a method with the same name on the SyscallInterface
class.
"""
OPEN_MODES = {
0: 'rb',
@ -39,7 +44,7 @@ class Syscall:
"""
id: int
"""The syscall number (e.g. 64 - write)"""
cpu: 'UserModeCPU'
cpu: CPU
"""The CPU object that created the syscall"""
@property
@ -95,7 +100,7 @@ class SyscallInterface:
addr = scall.cpu.regs.get('a1').unsigned_value
size = scall.cpu.regs.get('a2').unsigned_value
if fileno not in self.open_files:
scall.cpu.regs.set('a0', -1)
scall.ret(-1)
return
chars = self.open_files[fileno].readline(size)
@ -142,7 +147,7 @@ class SyscallInterface:
Requires running with flag scall-fs
"""
# FIXME: this should be toggleable in a global setting or somethign
# FIXME: this should be toggleable in a global setting or something
if True:
print(FMT_SYSCALL + '[Syscall] open: opening files not supported without scall-fs flag!' + FMT_NONE)
return scall.ret(-1)