3671582c15
The purpose of this is: * Only one way to do things * Changing a function with void return type to return a possible error becomes a 1 character change, subtly encouraging people to use errors. See #632 Here are some imperfect sed commands for performing this update: remove arrow: ``` sed -i 's/\(\bfn\b.*\)-> /\1/g' $(find . -name "*.zig") ``` add void: ``` sed -i 's/\(\bfn\b.*\))\s*{/\1) void {/g' $(find ../ -name "*.zig") ``` Some cleanup may be necessary, but this should do the bulk of the work.
131 lines
2.9 KiB
Zig
131 lines
2.9 KiB
Zig
// Special Cases:
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//
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// - ilogb(+-inf) = @maxValue(i32)
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// - ilogb(0) = @maxValue(i32)
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// - ilogb(nan) = @maxValue(i32)
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const std = @import("../index.zig");
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const math = std.math;
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const assert = std.debug.assert;
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pub fn ilogb(x: var) i32 {
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const T = @typeOf(x);
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return switch (T) {
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f32 => ilogb32(x),
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f64 => ilogb64(x),
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else => @compileError("ilogb not implemented for " ++ @typeName(T)),
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};
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}
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// NOTE: Should these be exposed publically?
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const fp_ilogbnan = -1 - i32(@maxValue(u32) >> 1);
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const fp_ilogb0 = fp_ilogbnan;
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fn ilogb32(x: f32) i32 {
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var u = @bitCast(u32, x);
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var e = i32((u >> 23) & 0xFF);
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// TODO: We should be able to merge this with the lower check.
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if (math.isNan(x)) {
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return @maxValue(i32);
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}
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if (e == 0) {
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u <<= 9;
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if (u == 0) {
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math.raiseInvalid();
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return fp_ilogb0;
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}
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// subnormal
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e = -0x7F;
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while (u >> 31 == 0) : (u <<= 1) {
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e -= 1;
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}
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return e;
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}
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if (e == 0xFF) {
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math.raiseInvalid();
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if (u << 9 != 0) {
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return fp_ilogbnan;
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} else {
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return @maxValue(i32);
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}
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}
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return e - 0x7F;
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}
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fn ilogb64(x: f64) i32 {
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var u = @bitCast(u64, x);
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var e = i32((u >> 52) & 0x7FF);
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if (math.isNan(x)) {
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return @maxValue(i32);
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}
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if (e == 0) {
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u <<= 12;
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if (u == 0) {
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math.raiseInvalid();
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return fp_ilogb0;
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}
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// subnormal
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e = -0x3FF;
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while (u >> 63 == 0) : (u <<= 1) {
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e -= 1;
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}
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return e;
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}
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if (e == 0x7FF) {
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math.raiseInvalid();
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if (u << 12 != 0) {
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return fp_ilogbnan;
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} else {
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return @maxValue(i32);
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}
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}
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return e - 0x3FF;
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}
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test "math.ilogb" {
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assert(ilogb(f32(0.2)) == ilogb32(0.2));
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assert(ilogb(f64(0.2)) == ilogb64(0.2));
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}
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test "math.ilogb32" {
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assert(ilogb32(0.0) == fp_ilogb0);
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assert(ilogb32(0.5) == -1);
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assert(ilogb32(0.8923) == -1);
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assert(ilogb32(10.0) == 3);
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assert(ilogb32(-123984) == 16);
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assert(ilogb32(2398.23) == 11);
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}
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test "math.ilogb64" {
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assert(ilogb64(0.0) == fp_ilogb0);
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assert(ilogb64(0.5) == -1);
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assert(ilogb64(0.8923) == -1);
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assert(ilogb64(10.0) == 3);
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assert(ilogb64(-123984) == 16);
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assert(ilogb64(2398.23) == 11);
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}
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test "math.ilogb32.special" {
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assert(ilogb32(math.inf(f32)) == @maxValue(i32));
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assert(ilogb32(-math.inf(f32)) == @maxValue(i32));
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assert(ilogb32(0.0) == @minValue(i32));
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assert(ilogb32(math.nan(f32)) == @maxValue(i32));
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}
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test "math.ilogb64.special" {
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assert(ilogb64(math.inf(f64)) == @maxValue(i32));
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assert(ilogb64(-math.inf(f64)) == @maxValue(i32));
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assert(ilogb64(0.0) == @minValue(i32));
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assert(ilogb64(math.nan(f64)) == @maxValue(i32));
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}
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