love/src/modules/sound/wrap_SoundData.lua

R"luastring"--(
-- DO NOT REMOVE THE ABOVE LINE. It is used to load this file as a C++ string.
-- There is a matching delimiter at the bottom of the file.

--[[
Copyright (c) 2006-2024 LOVE Development Team

This software is provided 'as-is', without any express or implied
warranty.  In no event will the authors be held liable for any damages
arising from the use of this software.

Permission is granted to anyone to use this software for any purpose,
including commercial applications, and to alter it and redistribute it
freely, subject to the following restrictions:

1. The origin of this software must not be misrepresented; you must not
claim that you wrote the original software. If you use this software
in a product, an acknowledgment in the product documentation would be
appreciated but is not required.
2. Altered source versions must be plainly marked as such, and must not be
misrepresented as being the original software.
3. This notice may not be removed or altered from any source distribution.
--]]

local SoundData_mt = ...
local SoundData = SoundData_mt.__index

if type(jit) ~= "table" or not jit.status() then
	-- LuaJIT's FFI is *much* slower than LOVE's regular methods when the JIT
	-- compiler is disabled.
	return
end

local status, ffi = pcall(require, "ffi")
if not status then return end

local tonumber, assert, error, type = tonumber, assert, error, type
local floor = math.floor

local float = ffi.typeof("float")
local datatypes = {ffi.typeof("uint8_t *"), ffi.typeof("int16_t *")}

local typemaxvals = {0x7F, 0x7FFF}

local _getBitDepth = SoundData.getBitDepth
local _getSampleCount = SoundData.getSampleCount
local _getSampleRate = SoundData.getSampleRate
local _getChannelCount = SoundData.getChannelCount
local _getDuration = SoundData.getDuration
local _release = SoundData.release

-- Table which holds SoundData objects as keys, and information about the objects
-- as values. Uses weak keys so the SoundData objects can still be GC'd properly.
local objectcache = setmetatable({}, {
	__mode = "k",
	__index = function(self, sounddata)
		local bytedepth = _getBitDepth(sounddata) / 8
		local pointer = ffi.cast(datatypes[bytedepth], sounddata:getFFIPointer())

		local p = {
			bytedepth = bytedepth,
			pointer = pointer,
			size = sounddata:getSize(),
			maxvalue = typemaxvals[bytedepth],
			samplecount = _getSampleCount(sounddata),
			samplerate = _getSampleRate(sounddata),
			channels = _getChannelCount(sounddata),
			duration = _getDuration(sounddata),
		}

		self[sounddata] = p
		return p
	end,
})


-- Overwrite existing functions with new FFI versions.

function SoundData:getSample(i, channel)
	if type(i) ~= "number" then error("bad argument #1 to SoundData:getSample (expected number)", 2) end
	if channel ~= nil and type(channel) ~= "number" then error("bad argument #2 to SoundData:getSample (expected number)", 2) end

	i = floor(i)

	local p = objectcache[self]

	if channel then
		if channel < 1 or channel > p.channels then
			error("Attempt to get sample from out-of-range channel!", 2)
		end
		i = i * p.channels + (channel-1)
	end

	if not (i >= 0 and i < p.size/p.bytedepth) then
		error("Attempt to get out-of-range sample!", 2)
	end

	if p.bytedepth == 2 then
		-- 16-bit data is stored as signed values internally.
		return tonumber(p.pointer[i]) / p.maxvalue
	else
		-- 8-bit data is stored as unsigned values internally.
		return (tonumber(p.pointer[i]) - 128) / 127
	end
end

function SoundData:setSample(i, channel, sample)
	if type(i) ~= "number" then error("bad argument #1 to SoundData:setSample (expected number)", 2) end
	if sample ~= nil then
		if type(channel) ~= "number" then error("bad argument #2 to SoundData:setSample (expected number)", 2) end
	else
		sample, channel = channel, nil
	end
	if type(sample) ~= "number" then error("bad argument #2 to SoundData:setSample (expected number)", 2) end

	i = floor(i)

	local p = objectcache[self]

	if channel then
		if channel < 1 or channel > p.channels then
			error("Attempt to set sample from out-of-range channel!", 2)
		end
		i = i * p.channels + (channel-1)
	end

	if not (i >= 0 and i < p.size/p.bytedepth) then
		error("Attempt to set out-of-range sample!", 2)
	end

	if p.bytedepth == 2 then
		-- 16-bit data is stored as signed values internally.
		p.pointer[i] = sample * p.maxvalue
	else
		-- 8-bit data is stored as unsigned values internally.
		-- The float cast is needed to make values end up the same as in the
		-- C++ version of this method.
		p.pointer[i] = ffi.cast(float, (sample * 127) + 128)
	end
end

function SoundData:getBitDepth()
	return objectcache[self].bytedepth * 8
end

function SoundData:getSampleCount()
	return objectcache[self].samplecount
end

function SoundData:getSampleRate()
	return objectcache[self].samplerate
end

function SoundData:getChannelCount()
	return objectcache[self].channels
end

function SoundData:getDuration()
	return objectcache[self].duration
end

function SoundData:release()
	objectcache[self] = nil
	return _release(self)
end

-- DO NOT REMOVE THE NEXT LINE. It is used to load this file as a C++ string.
--)luastring"--"