tiny.simd.construct

1const std = @import("std");23pub fn zero(comptime D: type) D.Vector {4    return @splat(0);5}67pub fn set(comptime D: type, value: D.Lane) D.Vector {8    return @splat(value);9}1011pub fn @"undefined"(comptime D: type) D.Vector {12    return undefined;13}1415pub fn dup128VecFromValues(16    comptime D: type,17    values: [128 / @bitSizeOf(D.Lane)]D.Lane,18) D.Vector {19    const lanes_per_block = 128 / @bitSizeOf(D.Lane);20    var result: D.Vector = undefined;21    inline for (0..D.lane_count) |index| {22        result[index] = values[index % lanes_per_block];23    }24    return result;25}2627pub fn maskedSetOr(28    comptime D: type,29    inactive: D.Vector,30    mask: D.Mask,31    value: D.Lane,32) D.Vector {33    return @select(D.Lane, mask, @as(D.Vector, @splat(value)), inactive);34}3536pub fn maskedSet(comptime D: type, mask: D.Mask, value: D.Lane) D.Vector {37    return maskedSetOr(D, @splat(0), mask, value);38}3940pub fn inf(comptime D: type) D.Vector {41    if (@typeInfo(D.Lane) != .float) @compileError("inf requires floating-point lanes");42    return @splat(std.math.inf(D.Lane));43}4445pub fn nan(comptime D: type) D.Vector {46    if (@typeInfo(D.Lane) != .float) @compileError("nan requires floating-point lanes");47    return @splat(std.math.nan(D.Lane));48}4950pub fn iota(comptime D: type, first: D.Lane) D.Vector {51    var result: D.Vector = undefined;52    inline for (0..D.lane_count) |index| {53        result[index] = iotaLane(D.Lane, first, index);54    }55    return result;56}5758pub fn firstN(comptime D: type, count: usize) D.Mask {59    var result: D.Mask = @splat(false);60    inline for (0..D.lane_count) |index| {61        result[index] = index < count;62    }63    return result;64}6566pub fn lane(comptime D: type, value: D.Vector, index: usize) D.Lane {67    std.debug.assert(index < D.lane_count);68    const values: [D.lane_count]D.Lane = value;69    return values[index];70}7172pub fn insertLane(73    comptime D: type,74    value: D.Vector,75    index: usize,76    inserted: D.Lane,77) D.Vector {78    std.debug.assert(index < D.lane_count);79    var values: [D.lane_count]D.Lane = value;80    values[index] = inserted;81    std.debug.assert(values[index] == inserted);82    return values;83}8485fn iotaLane(comptime T: type, first: T, index: usize) T {86    return switch (@typeInfo(T)) {87        .int => blk: {88            const U = @Int(.unsigned, @bitSizeOf(T));89            const first_bits: U = @bitCast(first);90            const offset: U = @truncate(index);91            break :blk @bitCast(first_bits +% offset);92        },93        .float => first + @as(T, @floatFromInt(index)),94        else => unreachable,95    };96}9798test "constructors reproduce Highway set and wrapping iota" {99    const simd = @import("root.zig");100    const D = simd.FixedTag(i8, 4);101    try std.testing.expect(@reduce(.And, set(D, 7) == @as(D.Vector, @splat(7))));102    const expected: D.Vector = .{ 126, 127, -128, -127 };103    try std.testing.expect(@reduce(.And, iota(D, 126) == expected));104    try std.testing.expect(@reduce(.And, zero(D) == @as(D.Vector, @splat(0))));105}106107test "firstN clamps naturally and lane insertion is isolated" {108    const simd = @import("root.zig");109    const D = simd.FixedTag(u32, 4);110    const all = firstN(D, 9);111    try std.testing.expect(@reduce(.And, all));112    const only_two: D.Mask = .{ true, true, false, false };113    try std.testing.expect(@reduce(.And, firstN(D, 2) == only_two));114    const changed = insertLane(D, zero(D), 2, 9);115    try std.testing.expectEqual(@as(u32, 9), lane(D, changed, 2));116    try std.testing.expectEqual(@as(u32, 0), lane(D, changed, 1));117}118119test "floating constants classify as Highway infinity and NaN" {120    const simd = @import("root.zig");121    inline for (.{ f16, f32, f64 }) |T| {122        const D = simd.FixedTag(T, 4);123        try std.testing.expect(@reduce(.And, inf(D) == @as(D.Vector, @splat(std.math.inf(T)))));124        try std.testing.expect(@reduce(.And, nan(D) != nan(D)));125    }126}127128test "Highway block constants and masked sets preserve their lane contracts" {129    const simd = @import("root.zig");130    const D = simd.FixedTag(u32, 8);131    const repeated = dup128VecFromValues(D, .{ 1, 2, 3, 4 });132    try std.testing.expect(@reduce(.And, repeated == @as(D.Vector, .{ 1, 2, 3, 4, 1, 2, 3, 4 })));133    const mask: D.Mask = .{ true, false, true, false, false, true, false, true };134    try std.testing.expect(@reduce(.And, maskedSet(D, mask, 7) ==135        @as(D.Vector, .{ 7, 0, 7, 0, 0, 7, 0, 7 })));136    try std.testing.expect(@reduce(.And, maskedSetOr(D, @splat(9), mask, 7) ==137        @as(D.Vector, .{ 7, 9, 7, 9, 9, 7, 9, 7 })));138}

1pub const construct = @import("construct.zig");