github.com/twelsh-aw/go/src@v0.0.0-20230516233729-a56fe86a7c81/runtime/cgo/asm_arm.s (about)

     1  // Copyright 2012 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  
     7  // Called by C code generated by cmd/cgo.
     8  // func crosscall2(fn, a unsafe.Pointer, n int32, ctxt uintptr)
     9  // Saves C callee-saved registers and calls cgocallback with three arguments.
    10  // fn is the PC of a func(a unsafe.Pointer) function.
    11  TEXT crosscall2(SB),NOSPLIT|NOFRAME,$0
    12  	SUB	$(8*9), R13 // Reserve space for the floating point registers.
    13  	// The C arguments arrive in R0, R1, R2, and R3. We want to
    14  	// pass R0, R1, and R3 to Go, so we push those on the stack.
    15  	// Also, save C callee-save registers R4-R12.
    16  	MOVM.WP	[R0, R1, R3, R4, R5, R6, R7, R8, R9, g, R11, R12], (R13)
    17  	// Finally, save the link register R14. This also puts the
    18  	// arguments we pushed for cgocallback where they need to be,
    19  	// starting at 4(R13).
    20  	MOVW.W	R14, -4(R13)
    21  
    22  	// Skip floating point registers on GOARM < 6.
    23  	MOVB    runtime·goarm(SB), R11
    24  	CMP $6, R11
    25  	BLT skipfpsave
    26  	MOVD	F8, (13*4+8*1)(R13)
    27  	MOVD	F9, (13*4+8*2)(R13)
    28  	MOVD	F10, (13*4+8*3)(R13)
    29  	MOVD	F11, (13*4+8*4)(R13)
    30  	MOVD	F12, (13*4+8*5)(R13)
    31  	MOVD	F13, (13*4+8*6)(R13)
    32  	MOVD	F14, (13*4+8*7)(R13)
    33  	MOVD	F15, (13*4+8*8)(R13)
    34  
    35  skipfpsave:
    36  	BL	runtime·load_g(SB)
    37  	// We set up the arguments to cgocallback when saving registers above.
    38  	BL	runtime·cgocallback(SB)
    39  
    40  	MOVB    runtime·goarm(SB), R11
    41  	CMP $6, R11
    42  	BLT skipfprest
    43  	MOVD	(13*4+8*1)(R13), F8
    44  	MOVD	(13*4+8*2)(R13), F9
    45  	MOVD	(13*4+8*3)(R13), F10
    46  	MOVD	(13*4+8*4)(R13), F11
    47  	MOVD	(13*4+8*5)(R13), F12
    48  	MOVD	(13*4+8*6)(R13), F13
    49  	MOVD	(13*4+8*7)(R13), F14
    50  	MOVD	(13*4+8*8)(R13), F15
    51  
    52  skipfprest:
    53  	MOVW.P	4(R13), R14
    54  	MOVM.IAW	(R13), [R0, R1, R3, R4, R5, R6, R7, R8, R9, g, R11, R12]
    55  	ADD	$(8*9), R13
    56  	MOVW	R14, R15