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4c16f9a3c3
This covers the majority of the functions as covered by the C99 specification for a math library. Code is adapted primarily from musl libc, with the pow and standard trigonometric functions adapted from the Go stdlib. Changes: - Remove assert expose in index and import as needed. - Add float log function and merge with existing base 2 integer implementation. See https://github.com/tiehuis/zig-fmath. See #374.
101 lines
2.1 KiB
Zig
101 lines
2.1 KiB
Zig
const math = @import("index.zig");
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const assert = @import("../debug.zig").assert;
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pub fn ilogb(x: var) -> i32 {
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const T = @typeOf(x);
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switch (T) {
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f32 => @inlineCall(ilogb32, x),
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f64 => @inlineCall(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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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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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 (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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e - 0x3FF
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}
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test "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 "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 "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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