Source file src/pkg/cmd/asm/internal/flags/flags.go

     1	// Copyright 2015 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	// Package flags implements top-level flags and the usage message for the assembler.
     6	package flags
     7	
     8	import (
     9		"cmd/internal/objabi"
    10		"flag"
    11		"fmt"
    12		"os"
    13		"path/filepath"
    14		"strings"
    15	)
    16	
    17	var (
    18		Debug      = flag.Bool("debug", false, "dump instructions as they are parsed")
    19		OutputFile = flag.String("o", "", "output file; default foo.o for /a/b/c/foo.s as first argument")
    20		PrintOut   = flag.Bool("S", false, "print assembly and machine code")
    21		TrimPath   = flag.String("trimpath", "", "remove prefix from recorded source file paths")
    22		Shared     = flag.Bool("shared", false, "generate code that can be linked into a shared library")
    23		Dynlink    = flag.Bool("dynlink", false, "support references to Go symbols defined in other shared libraries")
    24		AllErrors  = flag.Bool("e", false, "no limit on number of errors reported")
    25		SymABIs    = flag.Bool("gensymabis", false, "write symbol ABI information to output file, don't assemble")
    26	)
    27	
    28	var (
    29		D MultiFlag
    30		I MultiFlag
    31	)
    32	
    33	func init() {
    34		flag.Var(&D, "D", "predefined symbol with optional simple value -D=identifier=value; can be set multiple times")
    35		flag.Var(&I, "I", "include directory; can be set multiple times")
    36		objabi.AddVersionFlag() // -V
    37	}
    38	
    39	// MultiFlag allows setting a value multiple times to collect a list, as in -I=dir1 -I=dir2.
    40	type MultiFlag []string
    41	
    42	func (m *MultiFlag) String() string {
    43		if len(*m) == 0 {
    44			return ""
    45		}
    46		return fmt.Sprint(*m)
    47	}
    48	
    49	func (m *MultiFlag) Set(val string) error {
    50		(*m) = append(*m, val)
    51		return nil
    52	}
    53	
    54	func Usage() {
    55		fmt.Fprintf(os.Stderr, "usage: asm [options] file.s ...\n")
    56		fmt.Fprintf(os.Stderr, "Flags:\n")
    57		flag.PrintDefaults()
    58		os.Exit(2)
    59	}
    60	
    61	func Parse() {
    62		flag.Usage = Usage
    63		flag.Parse()
    64		if flag.NArg() == 0 {
    65			flag.Usage()
    66		}
    67	
    68		// Flag refinement.
    69		if *OutputFile == "" {
    70			if flag.NArg() != 1 {
    71				flag.Usage()
    72			}
    73			input := filepath.Base(flag.Arg(0))
    74			if strings.HasSuffix(input, ".s") {
    75				input = input[:len(input)-2]
    76			}
    77			*OutputFile = fmt.Sprintf("%s.o", input)
    78		}
    79	}
    80	

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