wincallback.go

     1  // Copyright 2014 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  //go:build ignore
     6  
     7  // Generate Windows callback assembly file.
     8  
     9  package main
    10  
    11  import (
    12  	"bytes"
    13  	"fmt"
    14  	"os"
    15  )
    16  
    17  const maxCallback = 2000
    18  
    19  func genasm386Amd64() {
    20  	var buf bytes.Buffer
    21  
    22  	buf.WriteString(`// Code generated by wincallback.go using 'go generate'. DO NOT EDIT.
    23  
    24  //go:build 386 || amd64
    25  
    26  #include "textflag.h"
    27  
    28  // runtime·callbackasm is called by external code to
    29  // execute Go implemented callback function. It is not
    30  // called from the start, instead runtime·compilecallback
    31  // always returns address into runtime·callbackasm offset
    32  // appropriately so different callbacks start with different
    33  // CALL instruction in runtime·callbackasm. This determines
    34  // which Go callback function is executed later on.
    35  
    36  TEXT runtime·callbackasm(SB),NOSPLIT|NOFRAME,$0
    37  `)
    38  	for i := 0; i < maxCallback; i++ {
    39  		buf.WriteString("\tCALL\truntime·callbackasm1(SB)\n")
    40  	}
    41  
    42  	filename := fmt.Sprintf("zcallback_windows.s")
    43  	err := os.WriteFile(filename, buf.Bytes(), 0666)
    44  	if err != nil {
    45  		fmt.Fprintf(os.Stderr, "wincallback: %s\n", err)
    46  		os.Exit(2)
    47  	}
    48  }
    49  
    50  func genasmArm64() {
    51  	var buf bytes.Buffer
    52  
    53  	buf.WriteString(`// Code generated by wincallback.go using 'go generate'. DO NOT EDIT.
    54  
    55  // External code calls into callbackasm at an offset corresponding
    56  // to the callback index. Callbackasm is a table of MOV and B instructions.
    57  // The MOV instruction loads R12 with the callback index, and the
    58  // B instruction branches to callbackasm1.
    59  // callbackasm1 takes the callback index from R12 and
    60  // indexes into an array that stores information about each callback.
    61  // It then calls the Go implementation for that callback.
    62  #include "textflag.h"
    63  
    64  TEXT runtime·callbackasm(SB),NOSPLIT|NOFRAME,$0
    65  `)
    66  	for i := 0; i < maxCallback; i++ {
    67  		fmt.Fprintf(&buf, "\tMOVD\t$%d, R12\n", i)
    68  		buf.WriteString("\tB\truntime·callbackasm1(SB)\n")
    69  	}
    70  
    71  	err := os.WriteFile("zcallback_windows_arm64.s", buf.Bytes(), 0666)
    72  	if err != nil {
    73  		fmt.Fprintf(os.Stderr, "wincallback: %s\n", err)
    74  		os.Exit(2)
    75  	}
    76  }
    77  
    78  func gengo() {
    79  	var buf bytes.Buffer
    80  
    81  	fmt.Fprintf(&buf, `// Code generated by wincallback.go using 'go generate'. DO NOT EDIT.
    82  
    83  package runtime
    84  
    85  const cb_max = %d // maximum number of windows callbacks allowed
    86  `, maxCallback)
    87  	err := os.WriteFile("zcallback_windows.go", buf.Bytes(), 0666)
    88  	if err != nil {
    89  		fmt.Fprintf(os.Stderr, "wincallback: %s\n", err)
    90  		os.Exit(2)
    91  	}
    92  }
    93  
    94  func main() {
    95  	genasm386Amd64()
    96  	genasmArm64()
    97  	gengo()
    98  }
    99
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