help.go

Documentation: github.com/jezek/xgb

     1  package xgb
     2  
     3  /*
     4  help.go is meant to contain a rough hodge podge of functions that are mainly
     5  used in the auto generated code. Indeed, several functions here are simple
     6  wrappers so that the sub-packages don't need to be smart about which stdlib
     7  packages to import.
     8  
     9  Also, the 'Get..' and 'Put..' functions are used through the core xgb package
    10  too. (xgbutil uses them too.)
    11  */
    12  
    13  import (
    14  	"fmt"
    15  	"strings"
    16  )
    17  
    18  // StringsJoin is an alias to strings.Join. It allows us to avoid having to
    19  // import 'strings' in each of the generated Go files.
    20  func StringsJoin(ss []string, sep string) string {
    21  	return strings.Join(ss, sep)
    22  }
    23  
    24  // Sprintf is so we don't need to import 'fmt' in the generated Go files.
    25  func Sprintf(format string, v ...interface{}) string {
    26  	return fmt.Sprintf(format, v...)
    27  }
    28  
    29  // Errorf is just a wrapper for fmt.Errorf. Exists for the same reason
    30  // that 'stringsJoin' and 'sprintf' exists.
    31  func Errorf(format string, v ...interface{}) error {
    32  	return fmt.Errorf(format, v...)
    33  }
    34  
    35  // Pad a length to align on 4 bytes.
    36  func Pad(n int) int {
    37  	return (n + 3) & ^3
    38  }
    39  
    40  // PopCount counts the number of bits set in a value list mask.
    41  func PopCount(mask0 int) int {
    42  	mask := uint32(mask0)
    43  	n := 0
    44  	for i := uint32(0); i < 32; i++ {
    45  		if mask&(1<<i) != 0 {
    46  			n++
    47  		}
    48  	}
    49  	return n
    50  }
    51  
    52  // Put16 takes a 16 bit integer and copies it into a byte slice.
    53  func Put16(buf []byte, v uint16) {
    54  	buf[0] = byte(v)
    55  	buf[1] = byte(v >> 8)
    56  }
    57  
    58  // Put32 takes a 32 bit integer and copies it into a byte slice.
    59  func Put32(buf []byte, v uint32) {
    60  	buf[0] = byte(v)
    61  	buf[1] = byte(v >> 8)
    62  	buf[2] = byte(v >> 16)
    63  	buf[3] = byte(v >> 24)
    64  }
    65  
    66  // Put64 takes a 64 bit integer and copies it into a byte slice.
    67  func Put64(buf []byte, v uint64) {
    68  	buf[0] = byte(v)
    69  	buf[1] = byte(v >> 8)
    70  	buf[2] = byte(v >> 16)
    71  	buf[3] = byte(v >> 24)
    72  	buf[4] = byte(v >> 32)
    73  	buf[5] = byte(v >> 40)
    74  	buf[6] = byte(v >> 48)
    75  	buf[7] = byte(v >> 56)
    76  }
    77  
    78  // Get16 constructs a 16 bit integer from the beginning of a byte slice.
    79  func Get16(buf []byte) uint16 {
    80  	v := uint16(buf[0])
    81  	v |= uint16(buf[1]) << 8
    82  	return v
    83  }
    84  
    85  // Get32 constructs a 32 bit integer from the beginning of a byte slice.
    86  func Get32(buf []byte) uint32 {
    87  	v := uint32(buf[0])
    88  	v |= uint32(buf[1]) << 8
    89  	v |= uint32(buf[2]) << 16
    90  	v |= uint32(buf[3]) << 24
    91  	return v
    92  }
    93  
    94  // Get64 constructs a 64 bit integer from the beginning of a byte slice.
    95  func Get64(buf []byte) uint64 {
    96  	v := uint64(buf[0])
    97  	v |= uint64(buf[1]) << 8
    98  	v |= uint64(buf[2]) << 16
    99  	v |= uint64(buf[3]) << 24
   100  	v |= uint64(buf[4]) << 32
   101  	v |= uint64(buf[5]) << 40
   102  	v |= uint64(buf[6]) << 48
   103  	v |= uint64(buf[7]) << 56
   104  	return v
   105  }
   106
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