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Replace all bit32 functions with bitwise operations #19

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Replace all bit32 functions with bitwise operations #19

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22 changes: 11 additions & 11 deletions midi.lua
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Original file line number Diff line number Diff line change
Expand Up @@ -73,10 +73,10 @@ local function parseVarInt(s, bits) -- parses multiple bytes as an integer
error("error parsing file")
end
bits = bits or 8
local mask = bit32.rshift(0xFF, 8 - bits)
local mask = 0xFF >> 8 - bits
local num = 0
for i = 1, s:len() do
num = num + bit32.lshift(bit32.band(s:byte(i), mask), (s:len() - i) * bits)
num = num + s:byte(i) & mask << (s:len() - i) * bits
end
return num
end
Expand Down Expand Up @@ -114,17 +114,17 @@ if format == 2 then
end

-- Figure out our time system and prepare accordingly.
local time = {division = bit32.band(0x8000, delta) == 0 and "tpb" or "fps"}
local time = {division = 0x8000 & delta == 0 and "tpb" or "fps"}
if time.division == "tpb" then
time.tpb = bit32.band(0x7FFF, delta)
time.tpb = 0x7FFF & delta
time.mspb = 500000
function time.tick()
return time.mspb / time.tpb
end
print(string.format("Time division is in %d ticks per beat.", time.tpb))
else
time.fps = bit32.band(0x7F00, delta)
time.tpf = bit32.band(0x00FF, delta)
time.fps = 0x7F00 & delta
time.tpf = 0x00FF & delta
function time.tick()
return 1000000 / (time.fps * time.tpf)
end
Expand Down Expand Up @@ -162,13 +162,13 @@ while true do
for i = 1, math.huge do
local part = read()
total = total .. part
if bit32.band(0x80, part:byte(1)) == 0 then
if 0x80 & part:byte(1) == 0 then
return parseVarInt(total, 7)
end
end
end
local function parseVoiceMessage(event)
local channel = bit32.band(0xF, event)
local channel = 0xF & event
local note = parseVarInt(read())
local velocity = parseVarInt(read())
return channel, note, velocity
Expand Down Expand Up @@ -196,7 +196,7 @@ while true do
error("corrupt file: could not find continuation of divided sysex event")
end
local event
if bit32.band(test, 0x80) == 0 then
if test & 0x80 == 0 then
if running == 0 then
error("corrupt file: invalid running status")
end
Expand All @@ -209,7 +209,7 @@ while true do
running = test
end
end
local status = bit32.band(0xF0, event)
local status = 0xF0 & event
if status == 0x80 then -- Note off.
local channel, note, velocity = parseVoiceMessage(event)
noteOff(cursor, channel, note, velocity)
Expand Down Expand Up @@ -382,4 +382,4 @@ for tick = 1, totalLength do
if instruments.flush then instruments.flush() end
end
if keyboard.isKeyDown(keyboard.keys.c) and keyboard.isControlDown() then os.exit() end
end
end