I also tried to make it use SSE, and that seems to work just fine
(MinGW on Win7 32). It needs a tiny wrapper-dll, because LuaJIT can't
directly call ffi-functions with vector arguments (yet!)- so I pass
them via pointers.
I only implemented single-precision-4-float addition for now anyway-
it's just a proof of concept, I think ffi- vector operations are
somewhere on Mike's TODO-list (maybe someone will even sponsor that
and we'll have it in a blink ;).
Every kind of opinion/feedback is much appreciated- I'm learning,
after all, and sometimes even a plain "you're doing it wrong" helps a
LOT ;)
It's used like this:
v4sf = require 'v4sf'
local a, b = v4sf(1, 2, 3, 4), v4sf(1, 0, 1, 0)
print(a+b) --intermediate result, don't keep a reference for too long!
local c = v4sf(a+b) --when you *need* to keep the value
print(c)
Here is the code:
local M = {_NAME = 'v4sf', _VERSION = '0.1', _DESCRIPTION = [[
Module for 4d-vectors, single precision.
Vectors are immutable once constructed.
Vectors returned by metamethods (addition, etc.) are only temporary values and
_MUST_ be copied if you want to keep a reference to them.
Construct new vectors by calling the module table itself or its new- function.
Functions:
- new(<number> a,<number> b,<number> c,<number> d)
returns<v4sf> A vector with elements a, b, c, d
- new(<v4sf> v)
returns<v4sf> A copy of vector v
Types:
-<v4sf>: A vector with 4 (single-precision-float) elements.
- __add(<v4sf> a,<v4sf> b) returns<v4sf> The sum of a and b
- __tostring(<v4sf> v)
returns<string> Temporary values are marked with a 'tmp '- prefix.
]]}
local ffi = require'ffi'
--[[Can't call SSE functions directly (LuaJIT NYI), so we have to cheat a bit.
lua_sse.c is compiled like this (MinGW gcc):
gcc -O2 -msse -shared -o lua_sse.dll lua_sse.c
and should look like this:
#include<xmmintrin.h>
void lua_mm_add_ps(__m128 *r, __m128 *a, __m128 *b) { *r =
_mm_add_ps(*a, *b); }
--]]
ffi.cdef[[
typedef float m128 __attribute__ ((__vector_size__ (16)));
void lua_mm_add_ps(m128 *r, m128 *a, m128 *b);
]]
local sse = ffi.load 'lua_sse'
do
local metatable
local ctype = ffi.typeof 'm128[1]'
local cBuffer = {}
local cBufferIdx = 1
local function new_tmp(a, b, c, d)
return setmetatable({tmp = true, cdata = ctype{{a, b, c, d}}}, metatable)
end
function M.new(a, b, c, d)
if type(a) == 'table' and getmetatable(a) == metatable then
--copy constructor
return setmetatable({cdata = ctype{{a[0], a[1], a[2], a[3]}}}, metatable)
end
return setmetatable({cdata = ctype{{a, b, c, d}}}, metatable)
end
metatable = {
__tostring = function(v)
if v.tmp then
return ("tmp v4sf: %g,%g,%g,%g"):format(v.cdata[0][0],
v.cdata[0][1], v.cdata[0][2], v.cdata[0][3])
else
return ("v4sf: %g,%g,%g,%g"):format(v.cdata[0][0],
v.cdata[0][1], v.cdata[0][2], v.cdata[0][3])
end
end,
__add = function(a, b)
local tmp = cBuffer[cBufferIdx]
sse.lua_mm_add_ps(tmp.cdata, a.cdata, b.cdata)
cBufferIdx = (cBufferIdx+1) % #cBuffer
return tmp
end,
__index = function(v, k)
if type(k) == 'number' and k>= 0 and k< 4 then
return v.cdata[0][k]
end
end,
__newindex = function(v, k, newValue)
error "Assigning to vectors is not allowed"
end
}
for i=1,10 do cBuffer[i] = new_tmp() end
setmetatable(M, {
__call = function(_, a, b, c, d) return M.new(a, b, c, d) end,
__tostring = function(m) return m._DESCRIPTION end,
})
end
return M
