65 lines
2.5 KiB
Zig
65 lines
2.5 KiB
Zig
const std = @import("std");
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const builtin = @import("builtin");
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const compiler_rt = @import("../compiler_rt.zig");
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const symbol = compiler_rt.symbol;
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comptime {
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symbol(&__bitreversesi2, "__bitreversesi2");
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symbol(&__bitreversedi2, "__bitreversedi2");
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symbol(&__bitreverseti2, "__bitreverseti2");
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}
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inline fn bitreverseXi2(comptime T: type, a: T) T {
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switch (@bitSizeOf(T)) {
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32 => {
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var t: T = a;
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t = ((t >> 1) & 0x55555555) | ((t & 0x55555555) << 1);
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t = ((t >> 2) & 0x33333333) | ((t & 0x33333333) << 2);
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t = ((t >> 4) & 0x0F0F0F0F) | ((t & 0x0F0F0F0F) << 4);
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t = ((t >> 8) & 0x00FF00FF) | ((t & 0x00FF00FF) << 8);
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t = (t >> 16) | (t << 16);
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return t;
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},
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64 => {
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var t: T = a;
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t = ((t >> 1) & 0x5555555555555555) | ((t & 0x5555555555555555) << 1);
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t = ((t >> 2) & 0x3333333333333333) | ((t & 0x3333333333333333) << 2);
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t = ((t >> 4) & 0x0F0F0F0F0F0F0F0F) | ((t & 0x0F0F0F0F0F0F0F0F) << 4);
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t = ((t >> 8) & 0x00FF00FF00FF00FF) | ((t & 0x00FF00FF00FF00FF) << 8);
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t = ((t >> 16) & 0x0000FFFF0000FFFF) | ((t & 0x0000FFFF0000FFFF) << 16);
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t = (t >> 32) | (t << 32);
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return t;
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},
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128 => {
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var t: T = a;
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t = ((t >> 1) & 0x55555555555555555555555555555555) | ((t & 0x55555555555555555555555555555555) << 1);
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t = ((t >> 2) & 0x33333333333333333333333333333333) | ((t & 0x33333333333333333333333333333333) << 2);
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t = ((t >> 4) & 0x0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F) | ((t & 0x0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F) << 4);
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t = ((t >> 8) & 0x00FF00FF00FF00FF00FF00FF00FF00FF) | ((t & 0x00FF00FF00FF00FF00FF00FF00FF00FF) << 8);
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t = ((t >> 16) & 0x0000FFFF0000FFFF0000FFFF0000FFFF) | ((t & 0x0000FFFF0000FFFF0000FFFF0000FFFF) << 16);
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t = ((t >> 32) & 0x00000000FFFFFFFF00000000FFFFFFFF) | ((t & 0x00000000FFFFFFFF00000000FFFFFFFF) << 32);
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t = (t >> 64) | (t << 64);
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return t;
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},
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else => unreachable,
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}
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}
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pub fn __bitreversesi2(a: u32) callconv(.c) u32 {
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return bitreverseXi2(u32, a);
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}
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pub fn __bitreversedi2(a: u64) callconv(.c) u64 {
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return bitreverseXi2(u64, a);
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}
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pub fn __bitreverseti2(a: u128) callconv(.c) u128 {
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return bitreverseXi2(u128, a);
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}
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test {
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_ = @import("bitreversesi2_test.zig");
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_ = @import("bitreversedi2_test.zig");
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_ = @import("bitreverseti2_test.zig");
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}
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