// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// System calls and other sys.stuff for 386, Darwin
// See http://fxr.watson.org/fxr/source/bsd/kern/syscalls.c?v=xnu-1228
// or /usr/include/sys/syscall.h (on a Mac) for system call numbers.

TEXT notok(SB),7,$0
	MOVL	$0xf1, 0xf1
	RET

// Exit the entire program (like C exit)
TEXT sys·Exit(SB),7,$0
	MOVL	$1, AX
	INT	$0x80
	CALL	notok(SB)
	RET

// Exit this OS thread (like pthread_exit, which eventually
// calls __bsdthread_terminate).
TEXT exit1(SB),7,$0
	MOVL	$361, AX
	INT	$0x80
	JAE 2(PC)
	CALL	notok(SB)
	RET

TEXT sys·write(SB),7,$0
	MOVL	$4, AX
	INT	$0x80
	JAE	2(PC)
	CALL	notok(SB)
	RET

TEXT sys·mmap(SB),7,$0
	MOVL	$197, AX
	INT	$0x80
	JAE	2(PC)
	CALL	notok(SB)
	RET

TEXT sigaction(SB),7,$0
	MOVL	$46, AX
	INT	$0x80
	JAE	2(PC)
	CALL	notok(SB)
	RET

// Sigtramp's job is to call the actual signal handler.
// It is called with the following arguments on the stack:
//	0(FP)	"return address" - ignored
//	4(FP)	actual handler
//	8(FP)	siginfo style - ignored
//	12(FP)	signal number
//	16(FP)	siginfo
//	20(FP)	context
TEXT sigtramp(SB),7,$40
	MOVL	4(FS), BP	// m
	MOVL	28(BP), BP	// m->gsignal
	MOVL	BP, 0(FS)	// g = m->gsignal

	MOVL	handler+4(FP), DI
	MOVL	signo+12(FP), AX
	MOVL	siginfo+16(FP), BX
	MOVL	context+20(FP), CX

	MOVL	AX, 0(SP)
	MOVL	BX, 4(SP)
	MOVL	CX, 8(SP)
	CALL	DI

	MOVL	context+20(FP), CX
	MOVL	style+8(FP), BX

	MOVL	$0, 0(SP)	// "caller PC" - ignored
	MOVL	CX, 4(SP)
	MOVL	BX, 8(SP)
	MOVL	$184, AX	// sigreturn(ucontext, infostyle)
	INT	$0x80
	CALL	notok(SB)
	RET

TEXT sigaltstack(SB),7,$0
	MOVL	$53, AX
	INT	$0x80
	JAE	2(PC)
	CALL	notok(SB)
	RET

TEXT bsdthread_create(SB),7,$0
	MOVL	$360, AX
	INT	$0x80
	JAE	2(PC)
	CALL	notok(SB)
	RET

TEXT bsdthread_register(SB),7,$40
	MOVL	$366, AX
	MOVL	$bsdthread_start(SB), 0(SP)	// threadstart
	MOVL	$0, 4(SP)	// wqthread, not used by us
	MOVL	$0, 8(SP)	// pthsize, not used by us
	MOVL	$0, 12(SP)	// paranoia
	MOVL	$0, 16(SP)
	MOVL	$0, 20(SP)
	INT	$0x80
	JAE	2(PC)
	CALL	notok(SB)
	RET

// Invoke Mach system call.
// Assumes system call number in AX,
// caller PC on stack, caller's caller PC next,
// and then the system call arguments.
//
// Can be used for BSD too, but we don't,
// because if you use this interface the BSD
// system call numbers need an extra field
// in the high 16 bits that seems to be the
// argument count in bytes but is not always.
// INT $0x80 works fine for those.
TEXT sysenter(SB),7,$0
	POPL	DX
	MOVL	SP, CX
	BYTE $0x0F; BYTE $0x34;  // SYSENTER
	// returns to DX with SP set to CX

TEXT mach_msg_trap(SB),7,$0
	MOVL	$-31, AX
	CALL	sysenter(SB)
	RET

TEXT mach_reply_port(SB),7,$0
	MOVL	$-26, AX
	CALL	sysenter(SB)
	RET

TEXT mach_task_self(SB),7,$0
	MOVL	$-28, AX
	CALL	sysenter(SB)
	RET

// Mach provides trap versions of the semaphore ops,
// instead of requiring the use of RPC.

// uint32 mach_semaphore_wait(uint32)
TEXT mach_semaphore_wait(SB),7,$0
	MOVL	$-36, AX
	CALL	sysenter(SB)
	RET

// uint32 mach_semaphore_timedwait(uint32, uint32, uint32)
TEXT mach_semaphore_timedwait(SB),7,$0
	MOVL	$-38, AX
	CALL	sysenter(SB)
	RET

// uint32 mach_semaphore_signal(uint32)
TEXT mach_semaphore_signal(SB),7,$0
	MOVL	$-33, AX
	CALL	sysenter(SB)
	RET

// uint32 mach_semaphore_signal_all(uint32)
TEXT mach_semaphore_signal_all(SB),7,$0
	MOVL	$-34, AX
	CALL	sysenter(SB)
	RET

/*
descriptor entry format for system call
is the native machine format, ugly as it is:

	2-byte limit
	3-byte base
	1-byte: 0x80=present, 0x60=dpl<<5, 0x1F=type
	1-byte: 0x80=limit is *4k, 0x40=32-bit operand size,
		0x0F=4 more bits of limit
	1 byte: 8 more bits of base

int i386_get_ldt(int, union ldt_entry *, int);
int i386_set_ldt(int, const union ldt_entry *, int);

*/

// setldt(int entry, int address, int limit)
TEXT setldt(SB),7,$32
	// set up data_desc
	LEAL	16(SP), AX	// struct data_desc
	MOVL	$0, 0(AX)
	MOVL	$0, 4(AX)

	MOVL	address+4(FP), BX	// aka base
	MOVW	BX, 2(AX)
	SHRL	$16, BX
	MOVB	BX, 4(AX)
	SHRL	$8, BX
	MOVB	BX, 7(AX)

	MOVL	limit+8(FP), BX
	MOVW	BX, 0(AX)
	SHRL	$16, BX
	ANDL	$0x0F, BX
	ORL	$0x40, BX		// 32-bit operand size
	MOVB	BX, 6(AX)

	MOVL	$0xF2, 5(AX)	// r/w data descriptor, dpl=3, present

	// call i386_set_ldt(entry, desc, 1)
	MOVL	entry+0(FP), BX
	MOVL	BX, 0(SP)
	MOVL	AX, 4(SP)
	MOVL	$1, 8(SP)
	CALL	i386_set_ldt(SB)
	RET

TEXT i386_set_ldt(SB),7,$0
	MOVL	$5, AX
	INT	$0x82	// sic
	JAE	2(PC)
	CALL	notok(SB)
	RET