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author | Alyssa Ross <hi@alyssa.is> | 2022-05-31 09:59:33 +0000 |
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committer | Alyssa Ross <hi@alyssa.is> | 2022-05-31 09:59:57 +0000 |
commit | 9ff36293d1e428cd7bf03e8d4b03611b6d361c28 (patch) | |
tree | 1ab51a42b868c55b83f6ccdb80371b9888739dd9 /lib/zip-int-bits.nix | |
parent | 1c4fcd0d4b0541e674ee56ace1053e23e562cc80 (diff) | |
parent | ddc3c396a51918043bb0faa6f676abd9562be62c (diff) | |
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Last good Nixpkgs for Weston+nouveau? archive
I came this commit hash to terwiz[m] on IRC, who is trying to figure out what the last version of Spectrum that worked on their NUC with Nvidia graphics is.
Diffstat (limited to 'lib/zip-int-bits.nix')
-rw-r--r-- | lib/zip-int-bits.nix | 39 |
1 files changed, 39 insertions, 0 deletions
diff --git a/lib/zip-int-bits.nix b/lib/zip-int-bits.nix new file mode 100644 index 00000000000..edbcdfe1e68 --- /dev/null +++ b/lib/zip-int-bits.nix @@ -0,0 +1,39 @@ +/* Helper function to implement a fallback for the bit operators + `bitAnd`, `bitOr` and `bitXOr` on older nix version. + See ./trivial.nix +*/ +f: x: y: + let + # (intToBits 6) -> [ 0 1 1 ] + intToBits = x: + if x == 0 || x == -1 then + [] + else + let + headbit = if (x / 2) * 2 != x then 1 else 0; # x & 1 + tailbits = if x < 0 then ((x + 1) / 2) - 1 else x / 2; # x >> 1 + in + [headbit] ++ (intToBits tailbits); + + # (bitsToInt [ 0 1 1 ] 0) -> 6 + # (bitsToInt [ 0 1 0 ] 1) -> -6 + bitsToInt = l: signum: + if l == [] then + (if signum == 0 then 0 else -1) + else + (builtins.head l) + (2 * (bitsToInt (builtins.tail l) signum)); + + xsignum = if x < 0 then 1 else 0; + ysignum = if y < 0 then 1 else 0; + zipListsWith' = fst: snd: + if fst==[] && snd==[] then + [] + else if fst==[] then + [(f xsignum (builtins.head snd))] ++ (zipListsWith' [] (builtins.tail snd)) + else if snd==[] then + [(f (builtins.head fst) ysignum )] ++ (zipListsWith' (builtins.tail fst) [] ) + else + [(f (builtins.head fst) (builtins.head snd))] ++ (zipListsWith' (builtins.tail fst) (builtins.tail snd)); + in + assert (builtins.isInt x) && (builtins.isInt y); + bitsToInt (zipListsWith' (intToBits x) (intToBits y)) (f xsignum ysignum) |