# Some OS-specific preliminaries for Soso.

# Memory layout
#
# 0x40000000 - 0x40001ffff - for ELF code+data
# 0x40002000 - 0x401ffffff - for heap
== code 0x40000000
== data 0x40001000

# Syscalls
#
# We don't have libc, so we need to know Soso's precise syscall layout.
# https://github.com/ozkl/soso/blob/master/kernel/syscalltable.h
== code

syscall_exit:  # status/ebx : int
    b8/copy-to-eax 8/imm32
    cd/syscall 0x80/imm8

syscall_read:  # fd/ebx : int, buf/ecx : address, size/edx : int -> nbytes-or-error/eax : int
    b8/copy-to-eax 2/imm32
    cd/syscall 0x80/imm8
    c3/return

syscall_write:  # fd/ebx : int, buf/ecx : address, size/edx : int -> nbytes-or-error/eax : int
    b8/copy-to-eax 3/imm32
    cd/syscall 0x80/imm8
    c3/return

syscall_open:  # filename/ebx : (address null-terminated-string), flags/ecx : int -> fd-or-error/eax : int
    b8/copy-to-eax 0/imm32
    cd/syscall 0x80/imm8
    c3/return

syscall_close:  # fd/ebx : int -> status/eax
    b8/copy-to-eax 1/imm32
    cd/syscall 0x80/imm8
    c3/return

# anonymous mmap not implemented