1 files changed, 81 insertions, 0 deletions
diff --git a/samples/wave.lua b/samples/wave.lua
new file mode 100755
index 0000000..9fd5adb
--- /dev/null
+++ b/samples/wave.lua
@@ -0,0 +1,81 @@
+#!/usr/bin/lua
+
+require "lspipat"
+
+function uint(bytes, val) -- binary integer decoding
+	return Len(bytes) % function(bin)
+		bin = littleEndian and bin or bin:reverse()
+
+		local n = 0
+		local base = 1
+
+		for _, c in ipairs{bin:byte(1, bytes)} do
+			n = n + base * c
+			base = base * 256
+		end
+
+		val(n)
+	end
+end
+
+function _uint(bytes, name) return uint(bytes, function(n) _G[name] = n end) end
+function _uint16(name) return _uint(2, name) end
+function _uint32(name) return _uint(4, name) end
+
+hnd = assert(io.open(arg[1]))
+
+file = hnd:read("*a")
+
+hnd:close()
+
+-- WAVE file "grammar"
+
+format = "fmt "
+       * _uint32 "FmtChunkSize"
+       * _Setcur "FmtStartPos"
+       	 * _uint16 "AudioFormat"
+	 * _uint16 "NumChannels"
+	 * _uint32 "SampleRate"
+	 * _uint32 "ByteRate"
+	 * _uint16 "BlockAlign"
+	 * _uint16 "BitsPerSample"
+	 * ( -function() return AudioFormat == 1 end
+	   + _uint16 "ExtraParamSize"
+	   * _Len    "ExtraParamSize" )
+       * Pos(function() return FmtStartPos + FmtChunkSize end)
+       * -function() return BitsPerSample % 8 == 0 and
+       			    BlockAlign == NumChannels * BitsPerSample/8 and
+       			    ByteRate == SampleRate * BlockAlign end
+
+data = "data"
+     * _uint32 "DataChunkSize"
+     * _Len    "DataChunkSize"
+
+misc = Len(4)
+     * _uint32 "MiscChunkSize"
+     * _Len    "MiscChunkSize"
+
+wave = (topattern("RIFF") + "RIFX")
+     % function(id) littleEndian = id == "RIFF" end
+     * _uint32 "ChunkSize"
+     * _Setcur "StartPos"
+       * "WAVE"
+       * Arbno(format + data + misc)
+     * Pos(function() return StartPos + ChunkSize end)
+     * -function() return DataChunkSize % BlockAlign == 0 end
+     * RPos(0)
+
+assert(file:smatch(wave, spipat.match_anchored),
+       arg[1].." is not a valid WAVE file!")
+
+print(string.format(
+"%s\
+Format:		%u\
+Channels:	%u\
+Samplerate:	%u Hz\
+Byterate:	%u Hz\
+Bits/Sample:	%u\
+Samples:	%u",
+arg[1],
+AudioFormat, NumChannels, SampleRate, ByteRate, BitsPerSample, DataChunkSize / BlockAlign))
+print(os.date("Length:\t\t%T", DataChunkSize / ByteRate + 60*60*23))