hsqoi

Haskell implementatin of the QOI image format.

Benchmarks

The baseline is the reference C code @ e9069e.

Taking a single big .png photo (5616×3744), with either 3 (RGB) or 4 (RGBA) channels and taking a minimum of 5 runs gives, on Core i7 3930k @ 4.0 GHz:

Implementation	Decoding, ms	, % of best C	Encoding, ms	, % of best C
C, gcc 11, -O3 -march=native	228	117%	264	102%
C, gcc 11, -O3	230	118%	260	100%
C, clang 13, -O3 -march=native	211	108%	356	137%
C, clang 13, -O3	195	100%	341	131%
Haskell, 3-channel	172	88%	226	87%
Haskell, 4-channel	187	96%	209	80%

Similarly for a 5120x2880 artwork:

Implementation	Decoding, ms	, % of best C	Encoding, ms	, % of best C
C, gcc 11, -O3 -march=native	90	130%	73	102%
C, gcc 11, -O3	88	128%	71	100%
C, clang 13, -O3 -march=native	69	100%	124	175%
C, clang 13, -O3	70	101%	124	175%
Haskell, 3-channel	55	79%	70	99%
Haskell, 4-channel	54	78%	72	102%

On Ryzen 3700X, for the photo:

Implementation	Decoding, ms	, % of best C	Encoding, ms	, % of best C
C, gcc 11, -O3 -march=native	179	121%	198	101%
C, gcc 11, -O3	174	118%	196	100%
C, clang 13, -O3 -march=native	158	107%	266	136%
C, clang 13, -O3	148	100%	252	129%
Haskell, 3-channel	132	89%	191	97%
Haskell, 4-channel	145	98%	141	72%

For the artwork:

Implementation	Decoding, ms	, % of best C	Encoding, ms	, % of best C
C, gcc 11, -O3 -march=native	68	117%	56	102%
C, gcc 11, -O3	66	114%	55	100%
C, clang 13, -O3 -march=native	60	103%	96	175%
C, clang 13, -O3	58	100%	90	164%
Haskell, 3-channel	48	83%	54	98%
Haskell, 4-channel	48	83%	52	95%