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asm_arm.s
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// Copyright 2012 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.
#include "textflag.h"
// Set the x_crosscall2_ptr C function pointer variable point to crosscall2.
// It's such a pointer chain: _crosscall2_ptr -> x_crosscall2_ptr -> crosscall2
// Use a local trampoline, to avoid taking the address of a dynamically exported
// function.
TEXT ·set_crosscall2(SB),NOSPLIT,$0-0
MOVW _crosscall2_ptr(SB), R1
MOVW $crosscall2_trampoline<>(SB), R2
MOVW R2, (R1)
RET
TEXT crosscall2_trampoline<>(SB),NOSPLIT,$0-0
JMP crosscall2(SB)
// Called by C code generated by cmd/cgo.
// func crosscall2(fn, a unsafe.Pointer, n int32, ctxt uintptr)
// Saves C callee-saved registers and calls cgocallback with three arguments.
// fn is the PC of a func(a unsafe.Pointer) function.
TEXT crosscall2(SB),NOSPLIT|NOFRAME,$0
SUB $(8*9), R13 // Reserve space for the floating point registers.
// The C arguments arrive in R0, R1, R2, and R3. We want to
// pass R0, R1, and R3 to Go, so we push those on the stack.
// Also, save C callee-save registers R4-R12.
MOVM.WP [R0, R1, R3, R4, R5, R6, R7, R8, R9, g, R11, R12], (R13)
// Finally, save the link register R14. This also puts the
// arguments we pushed for cgocallback where they need to be,
// starting at 4(R13).
MOVW.W R14, -4(R13)
// Skip floating point registers if goarmsoftfp!=0.
MOVB runtime·goarmsoftfp(SB), R11
CMP $0, R11
BNE skipfpsave
MOVD F8, (13*4+8*1)(R13)
MOVD F9, (13*4+8*2)(R13)
MOVD F10, (13*4+8*3)(R13)
MOVD F11, (13*4+8*4)(R13)
MOVD F12, (13*4+8*5)(R13)
MOVD F13, (13*4+8*6)(R13)
MOVD F14, (13*4+8*7)(R13)
MOVD F15, (13*4+8*8)(R13)
skipfpsave:
BL runtime·load_g(SB)
// We set up the arguments to cgocallback when saving registers above.
BL runtime·cgocallback(SB)
MOVB runtime·goarmsoftfp(SB), R11
CMP $0, R11
BNE skipfprest
MOVD (13*4+8*1)(R13), F8
MOVD (13*4+8*2)(R13), F9
MOVD (13*4+8*3)(R13), F10
MOVD (13*4+8*4)(R13), F11
MOVD (13*4+8*5)(R13), F12
MOVD (13*4+8*6)(R13), F13
MOVD (13*4+8*7)(R13), F14
MOVD (13*4+8*8)(R13), F15
skipfprest:
MOVW.P 4(R13), R14
MOVM.IAW (R13), [R0, R1, R3, R4, R5, R6, R7, R8, R9, g, R11, R12]
ADD $(8*9), R13
MOVW R14, R15