lua-buffer

AS3 ByteArray module for lua.

usage:

To add this module to lvm, call luaopen_bytearr when initialize the lua aux lib.

luaopen_bytearr(L);

constant

ByteArray.LITTLE_ENDIAN = 0
ByteArray.BIG_ENDIAN    = 1

constructor

create( [capacity[, endian]] ) Create an empty byte array.
init( [param1, param2, ...] ) Create a byte array with initial bytes. Parameters should be a list of number or table.
load( str[, endian] ) Create a byte array with lua string object for read data. This byte array is read-only.

return A ByteArray object.

local x = ByteArray.create()  -- create an empty byte array
local y = ByteArray.init( 0, 1, 2, 3 ) -- create a byte array with initial bytes
local z = ByteArray.load( "hello" ) -- create a byte array with a lua string object

indexing

Index start from 1 to length. If out of range, return -1.

local buf = ByteArray.init(2,3)
buf[2] = 2
print(buf[1]) -- 2
print(buf[2]) -- 2
print(buf[3]) -- -1

reading data

readByte() Read a 8-bit signed integer from byte array.
readUnsignedByte() Read a 8-bit unsigned integer from byte array.
readShort() Read a 16-bit signed integer from byte array.
readUnsignedShort() Read a 16-bit unsigned integer from byte array.
readInt() Read a 32-bit signed integer from byte array.
readUnsignedInt() Read a 32-bit unsigned integer from byte array.
readFloat() Read a 32-bit float from byte array.
readDouble() Read a 64-bit float from byte array.
readCString() Read a string end with \0 from byte array.
readString(n) Read a lua string with n bytes.

return Data read.

local buf = ByteArray.init( 1, 2, 3, 4, 5, 6 ) 
local a = buf:readByte() -- a == 1 
local b = buf:readUnsignedByte() -- b == 2 
local c = buf:readShort() -- c == 0x0403 

writing data

writeByte( s8 ) Write a 8-bit signed integer to byte array.
writeUnsignedByte( u8 ) Write a 8-bit unsigned integer to byte array.
writeShort( s16 ) Write a 16-bit signed integer to byte array.
writeUnsignedShort( u16 ) Write a 16-bit unsigned integer to byte array.
writeInt( s32 ) Write a 32-bit signed integer to byte array.
writeUnsignedInt( u32 ) Write a 32-bit unsigned integer to byte array.
writeFloat( f32 ) Write a 32-bit float to byte array.
writeDouble( f64 ) Write a 64-bit float to byte array.
writeCString( str ) Write a string end with \0 to byte array.
writeString( str ) Write a lua string, and no \0 append to the string. If read, write the len of str is advised.

return The ByteArray object itself.

local buf = ByteArray.create()
buf:writeByte(1):writeByte(2):writeInt(0x0403)

copying data between ByteArray object

readBytes( to[, offset, length] ) Read data to first parameter(a ByteArray object), the range for the target byte array is start from offset with length.
writeBytes( from[, offset, length] ) Write data from first parameter(a ByteArray object), the range for the data is start from offset with length.

return nil

local buf = ByteArray.init( 1, 2, 3, 4, 5 )
local d = ByteArray.create()
buf:readBytes( d )

clearing the ByteArray object

clear() Reset the object to an empty byte array.

return nil

local buf = ByteArray.init(1,2,3,4,5)
buf:clear()
print( buf.length ) -- 0

converting the ByteArray object to lua string

toString() Convert the object to a lua string which allow \0 inside.

return A lua string.

local buf = ByteArray.init( 49, 50, 51, 52, 53, 0, 54, 55 )
local str = buf:toString()
print( str, #str, string.byte(str, 6 ), string.byte(str, 7) )

slicing the array

slice(position_stat, position_end) The same behavior as slice in ECMAScript.

return A new ByteArray object.

local buf = ByteArray.init( 1,2,3,4,5,6 )
local sub = buf:slice( 1, -1 )
for i=1, #sub do print(sub[i]) end -- 2 3 4 5

member position

Start position for reading / writing data. Position is start from 0 to length.

local buf = ByteArray.init( 1, 2, 3, 4, 5 )
buf.position = 3
local d = ByteArray.create()
buf:readBytes( d ) -- buf = <4 5>
print( buf.position ) -- 5

member length

Set / get length.

local buf = ByteArray.init( 1,2,3,4,5,6,7 )
print( buf.length ) -- 7
buf.length = 4
for i=1, #buf do print(buf[i]) end -- 1 2 3 4

member endian

Set / get endian.

local buf = ByteArray.init(2,3)
buf.endian = ByteArray.LITTLE_ENDIAN