104 lines
2.3 KiB
ArmAsm
104 lines
2.3 KiB
ArmAsm
// SPDX-License-Identifier: Apache-2.0
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// SPDX-FileCopyrightText: 2022 The Ebitengine Authors
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//go:build darwin || linux || freebsd
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/*
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trampoline for emulating required C functions for cgo in go (see cgo.go)
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(we convert cdecl calling convention to go and vice-versa)
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Since we're called from go and call into C we can cheat a bit with the calling conventions:
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- in go all the registers are caller saved
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- in C we have a couple of callee saved registers
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=> we can use BX, R12, R13, R14, R15 instead of the stack
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C Calling convention cdecl used here (we only need integer args):
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1. arg: DI
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2. arg: SI
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3. arg: DX
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4. arg: CX
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5. arg: R8
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6. arg: R9
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We don't need floats with these functions -> AX=0
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return value will be in AX
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*/
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#include "textflag.h"
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#include "go_asm.h"
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// these trampolines map the gcc ABI to Go ABI and then calls into the Go equivalent functions.
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TEXT x_cgo_init_trampoline(SB), NOSPLIT, $16
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MOVQ DI, AX
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MOVQ SI, BX
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MOVQ ·x_cgo_init_call(SB), DX
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MOVQ (DX), CX
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CALL CX
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RET
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TEXT x_cgo_thread_start_trampoline(SB), NOSPLIT, $8
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MOVQ DI, AX
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MOVQ ·x_cgo_thread_start_call(SB), DX
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MOVQ (DX), CX
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CALL CX
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RET
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TEXT x_cgo_setenv_trampoline(SB), NOSPLIT, $8
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MOVQ DI, AX
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MOVQ ·x_cgo_setenv_call(SB), DX
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MOVQ (DX), CX
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CALL CX
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RET
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TEXT x_cgo_unsetenv_trampoline(SB), NOSPLIT, $8
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MOVQ DI, AX
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MOVQ ·x_cgo_unsetenv_call(SB), DX
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MOVQ (DX), CX
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CALL CX
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RET
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TEXT x_cgo_notify_runtime_init_done_trampoline(SB), NOSPLIT, $0
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CALL ·x_cgo_notify_runtime_init_done(SB)
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RET
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TEXT x_cgo_bindm_trampoline(SB), NOSPLIT, $0
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CALL ·x_cgo_bindm(SB)
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RET
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// func setg_trampoline(setg uintptr, g uintptr)
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TEXT ·setg_trampoline(SB), NOSPLIT, $0-16
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MOVQ G+8(FP), DI
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MOVQ setg+0(FP), BX
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XORL AX, AX
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CALL BX
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RET
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TEXT threadentry_trampoline(SB), NOSPLIT, $16
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MOVQ DI, AX
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MOVQ ·threadentry_call(SB), DX
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MOVQ (DX), CX
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CALL CX
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RET
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TEXT ·call5(SB), NOSPLIT, $0-56
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MOVQ fn+0(FP), BX
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MOVQ a1+8(FP), DI
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MOVQ a2+16(FP), SI
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MOVQ a3+24(FP), DX
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MOVQ a4+32(FP), CX
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MOVQ a5+40(FP), R8
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XORL AX, AX // no floats
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PUSHQ BP // save BP
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MOVQ SP, BP // save SP inside BP bc BP is callee-saved
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SUBQ $16, SP // allocate space for alignment
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ANDQ $-16, SP // align on 16 bytes for SSE
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CALL BX
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MOVQ BP, SP // get SP back
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POPQ BP // restore BP
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MOVQ AX, ret+48(FP)
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RET
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