// Copyright 2018 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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#include "go_asm.h"
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#include "textflag.h"
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// _rt0_wasm_js is not used itself. It only exists to mark the exported functions as alive.
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TEXT _rt0_wasm_js(SB),NOSPLIT,$0
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I32Const $wasm_export_run(SB)
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Drop
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I32Const $wasm_export_resume(SB)
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Drop
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I32Const $wasm_export_getsp(SB)
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Drop
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// wasm_export_run gets called from JavaScript. It initializes the Go runtime and executes Go code until it needs
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// to wait for an event. It does NOT follow the Go ABI. It has two WebAssembly parameters:
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// R0: argc (i32)
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// R1: argv (i32)
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TEXT wasm_export_run(SB),NOSPLIT,$0
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MOVD $runtime·wasmStack+m0Stack__size(SB), SP
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Get SP
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Get R0 // argc
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I64ExtendUI32
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I64Store $0
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Get SP
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Get R1 // argv
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I64ExtendUI32
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I64Store $8
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I32Const $runtime·rt0_go(SB)
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I32Const $16
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I32ShrU
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Set PC_F
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I32Const $0
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Set PC_B
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Call wasm_pc_f_loop(SB)
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Return
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// wasm_export_resume gets called from JavaScript. It resumes the execution of Go code until it needs to wait for
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// an event.
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TEXT wasm_export_resume(SB),NOSPLIT,$0
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I32Const $runtime·handleEvent(SB)
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I32Const $16
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I32ShrU
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Set PC_F
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I32Const $0
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Set PC_B
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Call wasm_pc_f_loop(SB)
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Return
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TEXT wasm_pc_f_loop(SB),NOSPLIT,$0
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// Call the function for the current PC_F. Repeat until PAUSE != 0 indicates pause or exit.
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// The WebAssembly stack may unwind, e.g. when switching goroutines.
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// The Go stack on the linear memory is then used to jump to the correct functions
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// with this loop, without having to restore the full WebAssembly stack.
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loop:
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Loop
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Get PC_F
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CallIndirect $0
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Drop
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Get PAUSE
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I32Eqz
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BrIf loop
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End
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I32Const $0
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Set PAUSE
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Return
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// wasm_export_getsp gets called from JavaScript to retrieve the SP.
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TEXT wasm_export_getsp(SB),NOSPLIT,$0
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Get SP
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Return
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TEXT runtime·pause(SB), NOSPLIT, $0-8
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MOVD newsp+0(FP), SP
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I32Const $1
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Set PAUSE
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RETUNWIND
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TEXT runtime·exit(SB), NOSPLIT, $0-4
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Call runtime·wasmExit(SB)
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Drop
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I32Const $1
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Set PAUSE
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RETUNWIND
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TEXT wasm_export_lib(SB),NOSPLIT,$0
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UNDEF
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