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if not modules then modules = { } end modules ['util-fil'] = {
version = 1.001,
comment = "companion to luat-lib.mkiv",
author = "Hans Hagen, PRAGMA-ADE, Hasselt NL",
copyright = "PRAGMA ADE / ConTeXt Development Team",
license = "see context related readme files"
}
local byte = string.byte
local char = string.char
local extract = bit32 and bit32.extract
local floor = math.floor
-- Here are a few helpers (the starting point were old ones I used for parsing
-- flac files). In Lua 5.3 we can probably do this better. Some code will move
-- here.
utilities = utilities or { }
local files = { }
utilities.files = files
local zerobased = { }
function files.open(filename,zb)
local f = io.open(filename,"rb")
if f then
zerobased[f] = zb or false
end
return f
end
function files.close(f)
zerobased[f] = nil
f:close()
end
function files.size(f)
return f:seek("end")
end
files.getsize = files.size
function files.setposition(f,n)
if zerobased[f] then
f:seek("set",n)
else
f:seek("set",n - 1)
end
end
function files.getposition(f)
if zerobased[f] then
return f:seek()
else
return f:seek() + 1
end
end
function files.look(f,n,chars)
local p = f:seek()
local s = f:read(n)
f:seek("set",p)
if chars then
return s
else
return byte(s,1,#s)
end
end
function files.skip(f,n)
if n == 1 then
f:read(n)
else
f:seek("set",f:seek()+n)
end
end
function files.readbyte(f)
return byte(f:read(1))
end
function files.readbytes(f,n)
return byte(f:read(n),1,n)
end
function files.readchar(f)
return f:read(1)
end
function files.readstring(f,n)
return f:read(n or 1)
end
function files.readinteger1(f) -- one byte
local n = byte(f:read(1))
if n >= 0x80 then
-- return n - 0xFF - 1
return n - 0x100
else
return n
end
end
files.readcardinal1 = files.readbyte -- one byte
files.readcardinal = files.readcardinal1
files.readinteger = files.readinteger1
function files.readcardinal2(f)
local a, b = byte(f:read(2),1,2)
return 0x100 * a + b
end
function files.readcardinal2le(f)
local b, a = byte(f:read(2),1,2)
return 0x100 * a + b
end
function files.readinteger2(f)
local a, b = byte(f:read(2),1,2)
local n = 0x100 * a + b
if n >= 0x8000 then
-- return n - 0xFFFF - 1
return n - 0x10000
else
return n
end
end
function files.readinteger2le(f)
local b, a = byte(f:read(2),1,2)
local n = 0x100 * a + b
if n >= 0x8000 then
-- return n - 0xFFFF - 1
return n - 0x10000
else
return n
end
end
function files.readcardinal3(f)
local a, b, c = byte(f:read(3),1,3)
return 0x10000 * a + 0x100 * b + c
end
function files.readcardinal3le(f)
local c, b, a = byte(f:read(3),1,3)
return 0x10000 * a + 0x100 * b + c
end
function files.readinteger3(f)
local a, b, c = byte(f:read(3),1,3)
local n = 0x10000 * a + 0x100 * b + c
if n >= 0x80000 then
-- return n - 0xFFFFFF - 1
return n - 0x1000000
else
return n
end
end
function files.readinteger3le(f)
local c, b, a = byte(f:read(3),1,3)
local n = 0x10000 * a + 0x100 * b + c
if n >= 0x80000 then
-- return n - 0xFFFFFF - 1
return n - 0x1000000
else
return n
end
end
function files.readcardinal4(f)
local a, b, c, d = byte(f:read(4),1,4)
return 0x1000000 * a + 0x10000 * b + 0x100 * c + d
end
function files.readcardinal4le(f)
local d, c, b, a = byte(f:read(4),1,4)
return 0x1000000 * a + 0x10000 * b + 0x100 * c + d
end
function files.readinteger4(f)
local a, b, c, d = byte(f:read(4),1,4)
local n = 0x1000000 * a + 0x10000 * b + 0x100 * c + d
if n >= 0x8000000 then
-- return n - 0xFFFFFFFF - 1
return n - 0x100000000
else
return n
end
end
function files.readinteger4le(f)
local d, c, b, a = byte(f:read(4),1,4)
local n = 0x1000000 * a + 0x10000 * b + 0x100 * c + d
if n >= 0x8000000 then
-- return n - 0xFFFFFFFF - 1
return n - 0x100000000
else
return n
end
end
function files.readfixed4(f)
local a, b, c, d = byte(f:read(4),1,4)
local n = 0x100 * a + b
if n >= 0x8000 then
-- return n - 0xFFFF - 1 + (0x100 * c + d)/0xFFFF
return n - 0x10000 + (0x100 * c + d)/0xFFFF
else
return n + (0x100 * c + d)/0xFFFF
end
end
if extract then
function files.read2dot14(f)
local a, b = byte(f:read(2),1,2)
local n = 0x100 * a + b
local m = extract(n,0,30)
if n > 0x7FFF then
n = extract(n,30,2)
return m/0x4000 - 4
else
n = extract(n,30,2)
return n + m/0x4000
end
end
end
function files.skipshort(f,n)
f:read(2*(n or 1))
end
function files.skiplong(f,n)
f:read(4*(n or 1))
end
-- writers (kind of slow)
function files.writecardinal2(f,n)
local a = char(n % 256)
n = floor(n/256)
local b = char(n % 256)
f:write(b,a)
end
function files.writecardinal4(f,n)
local a = char(n % 256)
n = floor(n/256)
local b = char(n % 256)
n = floor(n/256)
local c = char(n % 256)
n = floor(n/256)
local d = char(n % 256)
f:write(d,c,b,a)
end
function files.writestring(f,s)
f:write(char(byte(s,1,#s)))
end
function files.writebyte(f,b)
f:write(char(b))
end
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