121 lines
2.8 KiB
Zig
121 lines
2.8 KiB
Zig
// Ported from musl, which is licensed under the MIT license:
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// https://git.musl-libc.org/cgit/musl/tree/COPYRIGHT
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//
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// https://git.musl-libc.org/cgit/musl/tree/src/math/ceilf.c
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// https://git.musl-libc.org/cgit/musl/tree/src/math/ceil.c
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const builtin = @import("builtin");
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const std = @import("../std.zig");
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const math = std.math;
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const expect = std.testing.expect;
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/// Returns the least integer value greater than of equal to x.
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///
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/// Special Cases:
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/// - ceil(+-0) = +-0
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/// - ceil(+-inf) = +-inf
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/// - ceil(nan) = nan
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pub fn ceil(x: var) @typeOf(x) {
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const T = @typeOf(x);
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return switch (T) {
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f32 => ceil32(x),
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f64 => ceil64(x),
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else => @compileError("ceil not implemented for " ++ @typeName(T)),
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};
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}
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fn ceil32(x: f32) f32 {
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var u = @bitCast(u32, x);
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var e = @intCast(i32, (u >> 23) & 0xFF) - 0x7F;
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var m: u32 = undefined;
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// TODO: Shouldn't need this explicit check.
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if (x == 0.0) {
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return x;
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}
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if (e >= 23) {
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return x;
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} else if (e >= 0) {
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m = u32(0x007FFFFF) >> @intCast(u5, e);
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if (u & m == 0) {
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return x;
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}
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math.forceEval(x + 0x1.0p120);
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if (u >> 31 == 0) {
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u += m;
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}
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u &= ~m;
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return @bitCast(f32, u);
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} else {
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math.forceEval(x + 0x1.0p120);
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if (u >> 31 != 0) {
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return -0.0;
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} else {
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return 1.0;
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}
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}
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}
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fn ceil64(x: f64) f64 {
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const u = @bitCast(u64, x);
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const e = (u >> 52) & 0x7FF;
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var y: f64 = undefined;
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if (e >= 0x3FF + 52 or x == 0) {
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return x;
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}
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if (u >> 63 != 0) {
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y = x - math.f64_toint + math.f64_toint - x;
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} else {
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y = x + math.f64_toint - math.f64_toint - x;
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}
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if (e <= 0x3FF - 1) {
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math.forceEval(y);
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if (u >> 63 != 0) {
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return -0.0;
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} else {
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return 1.0;
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}
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} else if (y < 0) {
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return x + y + 1;
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} else {
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return x + y;
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}
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}
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test "math.ceil" {
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expect(ceil(f32(0.0)) == ceil32(0.0));
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expect(ceil(f64(0.0)) == ceil64(0.0));
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}
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test "math.ceil32" {
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expect(ceil32(1.3) == 2.0);
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expect(ceil32(-1.3) == -1.0);
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expect(ceil32(0.2) == 1.0);
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}
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test "math.ceil64" {
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expect(ceil64(1.3) == 2.0);
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expect(ceil64(-1.3) == -1.0);
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expect(ceil64(0.2) == 1.0);
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}
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test "math.ceil32.special" {
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expect(ceil32(0.0) == 0.0);
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expect(ceil32(-0.0) == -0.0);
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expect(math.isPositiveInf(ceil32(math.inf(f32))));
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expect(math.isNegativeInf(ceil32(-math.inf(f32))));
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expect(math.isNan(ceil32(math.nan(f32))));
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}
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test "math.ceil64.special" {
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expect(ceil64(0.0) == 0.0);
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expect(ceil64(-0.0) == -0.0);
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expect(math.isPositiveInf(ceil64(math.inf(f64))));
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expect(math.isNegativeInf(ceil64(-math.inf(f64))));
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expect(math.isNan(ceil64(math.nan(f64))));
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}
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