| // Copyright 2018 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 "go_asm.h" |
| #include "textflag.h" |
| |
| // _rt0_wasm_js is not used itself. It only exists to mark the exported functions as alive. |
| TEXT _rt0_wasm_js(SB),NOSPLIT,$0 |
| I32Const $wasm_export_run(SB) |
| Drop |
| I32Const $wasm_export_resume(SB) |
| Drop |
| I32Const $wasm_export_getsp(SB) |
| Drop |
| |
| // wasm_export_run gets called from JavaScript. It initializes the Go runtime and executes Go code until it needs |
| // to wait for an event. It does NOT follow the Go ABI. It has two WebAssembly parameters: |
| // R0: argc (i32) |
| // R1: argv (i32) |
| TEXT wasm_export_run(SB),NOSPLIT,$0 |
| MOVD $runtime·wasmStack+m0Stack__size(SB), SP |
| |
| Get SP |
| Get R0 // argc |
| I64ExtendI32U |
| I64Store $0 |
| |
| Get SP |
| Get R1 // argv |
| I64ExtendI32U |
| I64Store $8 |
| |
| I32Const $0 // entry PC_B |
| Call runtime·rt0_go(SB) |
| Drop |
| Call wasm_pc_f_loop(SB) |
| |
| Return |
| |
| // wasm_export_resume gets called from JavaScript. It resumes the execution of Go code until it needs to wait for |
| // an event. |
| TEXT wasm_export_resume(SB),NOSPLIT,$0 |
| I32Const $0 |
| Call runtime·handleEvent(SB) |
| Drop |
| Call wasm_pc_f_loop(SB) |
| |
| Return |
| |
| TEXT wasm_pc_f_loop(SB),NOSPLIT,$0 |
| // Call the function for the current PC_F. Repeat until PAUSE != 0 indicates pause or exit. |
| // The WebAssembly stack may unwind, e.g. when switching goroutines. |
| // The Go stack on the linear memory is then used to jump to the correct functions |
| // with this loop, without having to restore the full WebAssembly stack. |
| // It is expected to have a pending call before entering the loop, so check PAUSE first. |
| Get PAUSE |
| I32Eqz |
| If |
| loop: |
| Loop |
| // Get PC_B & PC_F from -8(SP) |
| Get SP |
| I32Const $8 |
| I32Sub |
| I32Load16U $0 // PC_B |
| |
| Get SP |
| I32Const $8 |
| I32Sub |
| I32Load16U $2 // PC_F |
| |
| CallIndirect $0 |
| Drop |
| |
| Get PAUSE |
| I32Eqz |
| BrIf loop |
| End |
| End |
| |
| I32Const $0 |
| Set PAUSE |
| |
| Return |
| |
| // wasm_export_getsp gets called from JavaScript to retrieve the SP. |
| TEXT wasm_export_getsp(SB),NOSPLIT,$0 |
| Get SP |
| Return |
| |
| TEXT runtime·pause(SB), NOSPLIT, $0-8 |
| MOVD newsp+0(FP), SP |
| I32Const $1 |
| Set PAUSE |
| RETUNWIND |
| |
| TEXT runtime·exit(SB), NOSPLIT, $0-4 |
| I32Const $0 |
| Call runtime·wasmExit(SB) |
| Drop |
| I32Const $1 |
| Set PAUSE |
| RETUNWIND |
| |
| TEXT wasm_export_lib(SB),NOSPLIT,$0 |
| UNDEF |
