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d29871977f
We already have a LICENSE file that covers the Zig Standard Library. We no longer need to remind everyone that the license is MIT in every single file. Previously this was introduced to clarify the situation for a fork of Zig that made Zig's LICENSE file harder to find, and replaced it with their own license that required annual payments to their company. However that fork now appears to be dead. So there is no need to reinforce the copyright notice in every single file.
25 lines
1.1 KiB
Zig
25 lines
1.1 KiB
Zig
const builtin = @import("builtin");
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const compiler_rt = @import("../compiler_rt.zig");
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// ported from llvm compiler-rt 8.0.0rc3 95e1c294cb0415a377a7b1d6c7c7d4f89e1c04e4
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pub fn __popcountdi2(a: i64) callconv(.C) i32 {
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var x2 = @bitCast(u64, a);
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x2 = x2 - ((x2 >> 1) & 0x5555555555555555);
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// Every 2 bits holds the sum of every pair of bits (32)
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x2 = ((x2 >> 2) & 0x3333333333333333) + (x2 & 0x3333333333333333);
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// Every 4 bits holds the sum of every 4-set of bits (3 significant bits) (16)
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x2 = (x2 + (x2 >> 4)) & 0x0F0F0F0F0F0F0F0F;
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// Every 8 bits holds the sum of every 8-set of bits (4 significant bits) (8)
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var x: u32 = @truncate(u32, x2 + (x2 >> 32));
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// The lower 32 bits hold four 16 bit sums (5 significant bits).
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// Upper 32 bits are garbage */
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x = x + (x >> 16);
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// The lower 16 bits hold two 32 bit sums (6 significant bits).
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// Upper 16 bits are garbage */
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return @bitCast(i32, (x + (x >> 8)) & 0x0000007F); // (7 significant bits)
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}
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test "import popcountdi2" {
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_ = @import("popcountdi2_test.zig");
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}
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