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Merge branch 'master' into v2.1

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Mike Pall
2022-06-23 09:10:43 +02:00
parent 0065cff7e0 2e98c3d064
commit 4c2441c16c
13 changed files with 82 additions and 82 deletions
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14
doc/ext_ffi.html
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@@ -157,7 +157,7 @@ call the binding function. Phew!
<h2 id="cdata">Motivating Example: Using C Data Structures</h2>
<p>
The FFI library allows you to create and access C&nbsp;data
structures. Of course the main use for this is for interfacing with
structures. Of course, the main use for this is for interfacing with
C&nbsp;functions. But they can be used stand-alone, too.
</p>
<p>
@@ -169,7 +169,7 @@ implemented with a big table holding lots of tiny tables. This imposes
both a substantial memory overhead as well as a performance overhead.
</p>
<p>
Here's a sketch of a library that operates on color images plus a
Here's a sketch of a library that operates on color images, plus a
simple benchmark. First, the plain Lua version:
</p>
<pre class="code">
@@ -184,7 +184,7 @@ local function image_ramp_green(n)
return img
end
local function image_to_grey(img, n)
local function image_to_gray(img, n)
for i=1,n do
local y = floor(0.3*img[i].red + 0.59*img[i].green + 0.11*img[i].blue)
img[i].red = y; img[i].green = y; img[i].blue = y
@@ -194,14 +194,14 @@ end
local N = 400*400
local img = image_ramp_green(N)
for i=1,1000 do
image_to_grey(img, N)
image_to_gray(img, N)
end
</pre>
<p>
This creates a table with 160.000 pixels, each of which is a table
holding four number values in the range of 0-255. First an image with
holding four number values in the range of 0-255. First, an image with
a green ramp is created (1D for simplicity), then the image is
converted to greyscale 1000 times. Yes, that's silly, but I was in
converted to grayscale 1000 times. Yes, that's silly, but I was in
need of a simple example ...
</p>
<p>
@@ -308,7 +308,7 @@ be more compact and faster. This is certainly true (by a factor of
~1.7x). Switching to a struct-of-arrays would help, too.
</p>
<p style="font-size: 8pt;">
However the resulting code would be less idiomatic and rather
However, the resulting code would be less idiomatic and rather
error-prone. And it still doesn't get even close to the performance of
the FFI version of the code. Also, high-level data structures cannot
be easily passed to other C&nbsp;functions, especially I/O functions,