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comparison gen/README @ 45:7955bed1d169

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*: add preliminary floating point support no x86 intrinsics just yet, but I did add altivec since it's (arguably) the simplest :)
author Paper <paper@tflc.us>
date Wed, 30 Apr 2025 18:36:38 -0400
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44:b0a3f0248ecc 45:7955bed1d169
1 These files are used to generate the actual implementation headers in
2 `include/vec/impl`.
3
4 All of them are basically compiled the same way:
5 gcc -o genIMPL genIMPL.c genlib.c
6
7 You can generally base any new implementations off of one of the existing
8 ones. Preferably, you would base it off the generic implementation, since
9 it actually has all of the operations implemented (and serves as a
10 reference as to how these operations *should* work). For example the avg
11 operation on integers should be roughly equivalent to:
12 ceil((vec1 + vec2) / 2)
13
14 Note how it always rounds up, rather than truncating towards zero. This
15 is an important implementation detail, and stems from roots in AltiVec,
16 as it was the inspiration behind much of the vec API.
17
18 Note however, that avg has a different result with floating points that
19 is equivalent to simply
20 ((vec1 + vec2) / 2)
21 as there is no real way to get around any possible truncation.
22
23 Any overflow on integer operations should simply wrap around.