github.com/dorkamotorka/go/src@v0.0.0-20230614113921-187095f0e316/runtime/cgo/asm_amd64.s (about)

     1  // Copyright 2009 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  #include "textflag.h"
     6  #include "abi_amd64.h"
     7  
     8  // Set the x_crosscall2_ptr C function pointer variable point to crosscall2.
     9  // It's such a pointer chain: _crosscall2_ptr -> x_crosscall2_ptr -> crosscall2
    10  TEXT ·set_crosscall2(SB),NOSPLIT,$0-0
    11  	MOVQ	_crosscall2_ptr(SB), AX
    12  	MOVQ	$crosscall2(SB), BX
    13  	MOVQ	BX, (AX)
    14  	RET
    15  
    16  // Called by C code generated by cmd/cgo.
    17  // func crosscall2(fn, a unsafe.Pointer, n int32, ctxt uintptr)
    18  // Saves C callee-saved registers and calls cgocallback with three arguments.
    19  // fn is the PC of a func(a unsafe.Pointer) function.
    20  // This signature is known to SWIG, so we can't change it.
    21  TEXT crosscall2(SB),NOSPLIT|NOFRAME,$0-0
    22  	PUSH_REGS_HOST_TO_ABI0()
    23  
    24  	// Make room for arguments to cgocallback.
    25  	ADJSP	$0x18
    26  #ifndef GOOS_windows
    27  	MOVQ	DI, 0x0(SP)	/* fn */
    28  	MOVQ	SI, 0x8(SP)	/* arg */
    29  	// Skip n in DX.
    30  	MOVQ	CX, 0x10(SP)	/* ctxt */
    31  #else
    32  	MOVQ	CX, 0x0(SP)	/* fn */
    33  	MOVQ	DX, 0x8(SP)	/* arg */
    34  	// Skip n in R8.
    35  	MOVQ	R9, 0x10(SP)	/* ctxt */
    36  #endif
    37  
    38  	CALL	runtime·cgocallback(SB)
    39  
    40  	ADJSP	$-0x18
    41  	POP_REGS_HOST_TO_ABI0()
    42  	RET