1 files changed, 167 insertions, 0 deletions
diff --git a/lualibs-util-fil.lua b/lualibs-util-fil.lua
new file mode 100644
index 0000000..28c92c7
--- /dev/null
+++ b/lualibs-util-fil.lua
@@ -0,0 +1,167 @@
+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 extract = bit32.extract
+
+-- 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
+
+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
+    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.readinteger2(f)
+    local a, b = byte(f:read(2),1,2)
+    local n = 0x100 * a + b
+    if n >= 0x8000 then
+        return n - 0xFFFF - 1
+    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.readcardinal4(f)
+    local a, b, c, d = 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
+    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
+    else
+        return n              + (0x100 * c + d)/0xFFFF
+    end
+end
+
+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
+
+function files.skipshort(f,n)
+    f:read(2*(n or 1))
+end
+
+function files.skiplong(f,n)
+    f:read(4*(n or 1))
+end