mirror of
https://github.com/ziglang/zig.git
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256 lines
13 KiB
Zig
256 lines
13 KiB
Zig
const std = @import("std");
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const math = std.math;
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const testing = std.testing;
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const expect = testing.expect;
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const expectEqual = testing.expectEqual;
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const expectError = testing.expectError;
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const approxEqAbs = std.math.approxEqAbs;
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const epsilon = 1e-7;
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const parse = @import("parse_float/parse.zig");
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const convertHex = @import("parse_float/convert_hex.zig").convertHex;
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const convertFast = @import("parse_float/convert_fast.zig").convertFast;
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const convertEiselLemire = @import("parse_float/convert_eisel_lemire.zig").convertEiselLemire;
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const convertSlow = @import("parse_float/convert_slow.zig").convertSlow;
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pub const ParseFloatError = error{
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InvalidCharacter,
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};
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pub fn parseFloat(comptime T: type, s: []const u8) ParseFloatError!T {
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if (@typeInfo(T) != .Float) {
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@compileError("Cannot parse a float into a non-floating point type.");
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}
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if (s.len == 0) {
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return error.InvalidCharacter;
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}
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var i: usize = 0;
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const negative = s[i] == '-';
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if (s[i] == '-' or s[i] == '+') {
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i += 1;
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}
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if (s.len == i) {
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return error.InvalidCharacter;
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}
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const n = parse.parseNumber(T, s[i..], negative) orelse {
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return parse.parseInfOrNan(T, s[i..], negative) orelse error.InvalidCharacter;
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};
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if (n.hex) {
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return convertHex(T, n);
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}
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if (convertFast(T, n)) |f| {
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return f;
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}
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if (T == f16 or T == f32 or T == f64) {
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// If significant digits were truncated, then we can have rounding error
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// only if `mantissa + 1` produces a different result. We also avoid
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// redundantly using the Eisel-Lemire algorithm if it was unable to
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// correctly round on the first pass.
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if (convertEiselLemire(T, n.exponent, n.mantissa)) |bf| {
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if (!n.many_digits) {
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return bf.toFloat(T, n.negative);
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}
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if (convertEiselLemire(T, n.exponent, n.mantissa + 1)) |bf2| {
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if (bf.eql(bf2)) {
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return bf.toFloat(T, n.negative);
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}
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}
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}
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}
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// Unable to correctly round the float using the Eisel-Lemire algorithm.
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// Fallback to a slower, but always correct algorithm.
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return convertSlow(T, s[i..]).toFloat(T, negative);
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}
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// See https://github.com/tiehuis/parse-number-fxx-test-data for a wider-selection of test-data.
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test parseFloat {
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inline for ([_]type{ f16, f32, f64, f80, f128 }) |T| {
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try testing.expectError(error.InvalidCharacter, parseFloat(T, ""));
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try testing.expectError(error.InvalidCharacter, parseFloat(T, " 1"));
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try testing.expectError(error.InvalidCharacter, parseFloat(T, "1abc"));
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try testing.expectError(error.InvalidCharacter, parseFloat(T, "+"));
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try testing.expectError(error.InvalidCharacter, parseFloat(T, "-"));
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try expectEqual(try parseFloat(T, "0"), 0.0);
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try expectEqual(try parseFloat(T, "0"), 0.0);
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try expectEqual(try parseFloat(T, "+0"), 0.0);
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try expectEqual(try parseFloat(T, "-0"), 0.0);
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try expectEqual(try parseFloat(T, "0e0"), 0);
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try expectEqual(try parseFloat(T, "2e3"), 2000.0);
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try expectEqual(try parseFloat(T, "1e0"), 1.0);
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try expectEqual(try parseFloat(T, "-2e3"), -2000.0);
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try expectEqual(try parseFloat(T, "-1e0"), -1.0);
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try expectEqual(try parseFloat(T, "1.234e3"), 1234);
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try expect(approxEqAbs(T, try parseFloat(T, "3.141"), 3.141, epsilon));
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try expect(approxEqAbs(T, try parseFloat(T, "-3.141"), -3.141, epsilon));
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try expectEqual(try parseFloat(T, "1e-5000"), 0);
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try expectEqual(try parseFloat(T, "1e+5000"), std.math.inf(T));
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try expectEqual(try parseFloat(T, "0.4e0066999999999999999999999999999999999999999999999999999"), std.math.inf(T));
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try expect(approxEqAbs(T, try parseFloat(T, "0_1_2_3_4_5_6.7_8_9_0_0_0e0_0_1_0"), @as(T, 123456.789000e10), epsilon));
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// underscore rule is simple and reduces to "can only occur between two digits" and multiple are not supported.
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try expectError(error.InvalidCharacter, parseFloat(T, "0123456.789000e_0010")); // cannot occur immediately after exponent
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try expectError(error.InvalidCharacter, parseFloat(T, "_0123456.789000e0010")); // cannot occur before any digits
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try expectError(error.InvalidCharacter, parseFloat(T, "0__123456.789000e_0010")); // cannot occur twice in a row
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try expectError(error.InvalidCharacter, parseFloat(T, "0123456_.789000e0010")); // cannot occur before decimal point
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try expectError(error.InvalidCharacter, parseFloat(T, "0123456.789000e0010_")); // cannot occur at end of number
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try expect(approxEqAbs(T, try parseFloat(T, "1e-2"), 0.01, epsilon));
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try expect(approxEqAbs(T, try parseFloat(T, "1234e-2"), 12.34, epsilon));
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try expect(approxEqAbs(T, try parseFloat(T, "1."), 1, epsilon));
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try expect(approxEqAbs(T, try parseFloat(T, "0."), 0, epsilon));
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try expect(approxEqAbs(T, try parseFloat(T, ".1"), 0.1, epsilon));
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try expect(approxEqAbs(T, try parseFloat(T, ".0"), 0, epsilon));
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try expect(approxEqAbs(T, try parseFloat(T, ".1e-1"), 0.01, epsilon));
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try expectError(error.InvalidCharacter, parseFloat(T, ".")); // At least one digit is required.
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try expectError(error.InvalidCharacter, parseFloat(T, ".e1")); // At least one digit is required.
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try expectError(error.InvalidCharacter, parseFloat(T, "0.e")); // At least one digit is required.
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try expect(approxEqAbs(T, try parseFloat(T, "123142.1"), 123142.1, epsilon));
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try expect(approxEqAbs(T, try parseFloat(T, "-123142.1124"), @as(T, -123142.1124), epsilon));
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try expect(approxEqAbs(T, try parseFloat(T, "0.7062146892655368"), @as(T, 0.7062146892655368), epsilon));
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try expect(approxEqAbs(T, try parseFloat(T, "2.71828182845904523536"), @as(T, 2.718281828459045), epsilon));
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}
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}
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test "nan and inf" {
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inline for ([_]type{ f16, f32, f64, f80, f128 }) |T| {
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const Z = std.meta.Int(.unsigned, @typeInfo(T).Float.bits);
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try expectEqual(@as(Z, @bitCast(try parseFloat(T, "nAn"))), @as(Z, @bitCast(std.math.nan(T))));
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try expectEqual(try parseFloat(T, "inF"), std.math.inf(T));
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try expectEqual(try parseFloat(T, "-INF"), -std.math.inf(T));
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}
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}
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test "largest normals" {
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try expectEqual(@as(u16, @bitCast(try parseFloat(f16, "65504"))), 0x7bff);
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try expectEqual(@as(u32, @bitCast(try parseFloat(f32, "3.4028234664E38"))), 0x7f7f_ffff);
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try expectEqual(@as(u64, @bitCast(try parseFloat(f64, "1.7976931348623157E308"))), 0x7fef_ffff_ffff_ffff);
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try expectEqual(@as(u80, @bitCast(try parseFloat(f80, "1.189731495357231765E4932"))), 0x7ffe_ffff_ffff_ffff_ffff);
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try expectEqual(@as(u128, @bitCast(try parseFloat(f128, "1.1897314953572317650857593266280070162E4932"))), 0x7ffe_ffff_ffff_ffff_ffff_ffff_ffff_ffff);
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}
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test "#11169" {
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try expectEqual(try parseFloat(f128, "9007199254740993.0"), 9007199254740993.0);
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}
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test "many_digits hex" {
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const a: f32 = try parseFloat(f32, "0xffffffffffffffff.0p0");
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const b: f32 = @floatCast(try parseFloat(f128, "0xffffffffffffffff.0p0"));
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try std.testing.expectEqual(a, b);
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}
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test "hex.special" {
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try testing.expect(math.isNan(try parseFloat(f32, "nAn")));
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try testing.expect(math.isPositiveInf(try parseFloat(f32, "iNf")));
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try testing.expect(math.isPositiveInf(try parseFloat(f32, "+Inf")));
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try testing.expect(math.isNegativeInf(try parseFloat(f32, "-iNf")));
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}
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test "hex.zero" {
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try testing.expectEqual(@as(f32, 0.0), try parseFloat(f32, "0x0"));
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try testing.expectEqual(@as(f32, 0.0), try parseFloat(f32, "-0x0"));
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try testing.expectEqual(@as(f32, 0.0), try parseFloat(f32, "0x0p42"));
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try testing.expectEqual(@as(f32, 0.0), try parseFloat(f32, "-0x0.00000p42"));
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try testing.expectEqual(@as(f32, 0.0), try parseFloat(f32, "0x0.00000p666"));
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}
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test "hex.f16" {
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try testing.expectEqual(try parseFloat(f16, "0x1p0"), 1.0);
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try testing.expectEqual(try parseFloat(f16, "-0x1p-1"), -0.5);
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try testing.expectEqual(try parseFloat(f16, "0x10p+10"), 16384.0);
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try testing.expectEqual(try parseFloat(f16, "0x10p-10"), 0.015625);
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// Max normalized value.
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try testing.expectEqual(try parseFloat(f16, "0x1.ffcp+15"), math.floatMax(f16));
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try testing.expectEqual(try parseFloat(f16, "-0x1.ffcp+15"), -math.floatMax(f16));
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// Min normalized value.
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try testing.expectEqual(try parseFloat(f16, "0x1p-14"), math.floatMin(f16));
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try testing.expectEqual(try parseFloat(f16, "-0x1p-14"), -math.floatMin(f16));
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// Min denormal value.
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try testing.expectEqual(try parseFloat(f16, "0x1p-24"), math.floatTrueMin(f16));
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try testing.expectEqual(try parseFloat(f16, "-0x1p-24"), -math.floatTrueMin(f16));
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}
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test "hex.f32" {
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try testing.expectError(error.InvalidCharacter, parseFloat(f32, "0x"));
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try testing.expectEqual(try parseFloat(f32, "0x1p0"), 1.0);
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try testing.expectEqual(try parseFloat(f32, "-0x1p-1"), -0.5);
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try testing.expectEqual(try parseFloat(f32, "0x10p+10"), 16384.0);
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try testing.expectEqual(try parseFloat(f32, "0x10p-10"), 0.015625);
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try testing.expectEqual(try parseFloat(f32, "0x0.ffffffp128"), 0x0.ffffffp128);
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try testing.expectEqual(try parseFloat(f32, "0x0.1234570p-125"), 0x0.1234570p-125);
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// Max normalized value.
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try testing.expectEqual(try parseFloat(f32, "0x1.fffffeP+127"), math.floatMax(f32));
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try testing.expectEqual(try parseFloat(f32, "-0x1.fffffeP+127"), -math.floatMax(f32));
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// Min normalized value.
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try testing.expectEqual(try parseFloat(f32, "0x1p-126"), math.floatMin(f32));
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try testing.expectEqual(try parseFloat(f32, "-0x1p-126"), -math.floatMin(f32));
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// Min denormal value.
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try testing.expectEqual(try parseFloat(f32, "0x1P-149"), math.floatTrueMin(f32));
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try testing.expectEqual(try parseFloat(f32, "-0x1P-149"), -math.floatTrueMin(f32));
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}
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test "hex.f64" {
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try testing.expectEqual(try parseFloat(f64, "0x1p0"), 1.0);
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try testing.expectEqual(try parseFloat(f64, "-0x1p-1"), -0.5);
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try testing.expectEqual(try parseFloat(f64, "0x10p+10"), 16384.0);
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try testing.expectEqual(try parseFloat(f64, "0x10p-10"), 0.015625);
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// Max normalized value.
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try testing.expectEqual(try parseFloat(f64, "0x1.fffffffffffffp+1023"), math.floatMax(f64));
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try testing.expectEqual(try parseFloat(f64, "-0x1.fffffffffffffp1023"), -math.floatMax(f64));
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// Min normalized value.
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try testing.expectEqual(try parseFloat(f64, "0x1p-1022"), math.floatMin(f64));
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try testing.expectEqual(try parseFloat(f64, "-0x1p-1022"), -math.floatMin(f64));
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// Min denormalized value.
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try testing.expectEqual(try parseFloat(f64, "0x1p-1074"), math.floatTrueMin(f64));
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try testing.expectEqual(try parseFloat(f64, "-0x1p-1074"), -math.floatTrueMin(f64));
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}
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test "hex.f80" {
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try testing.expectEqual(try parseFloat(f80, "0x1p0"), 1.0);
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try testing.expectEqual(try parseFloat(f80, "-0x1p-1"), -0.5);
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try testing.expectEqual(try parseFloat(f80, "0x10p+10"), 16384.0);
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try testing.expectEqual(try parseFloat(f80, "0x10p-10"), 0.015625);
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// Max normalized value.
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try testing.expectEqual(try parseFloat(f80, "0xf.fffffffffffffff7p+16380"), math.floatMax(f80));
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try testing.expectEqual(try parseFloat(f80, "-0xf.fffffffffffffff7p+16380"), -math.floatMax(f80));
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// Min normalized value.
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try testing.expectEqual(try parseFloat(f80, "0x1p-16382"), math.floatMin(f80));
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try testing.expectEqual(try parseFloat(f80, "-0x1p-16382"), -math.floatMin(f80));
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// Min denormalized value.
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try testing.expectEqual(try parseFloat(f80, "0x1p-16445"), math.floatTrueMin(f80));
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try testing.expectEqual(try parseFloat(f80, "-0x1p-16445"), -math.floatTrueMin(f80));
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}
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test "hex.f128" {
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try testing.expectEqual(try parseFloat(f128, "0x1p0"), 1.0);
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try testing.expectEqual(try parseFloat(f128, "-0x1p-1"), -0.5);
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try testing.expectEqual(try parseFloat(f128, "0x10p+10"), 16384.0);
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try testing.expectEqual(try parseFloat(f128, "0x10p-10"), 0.015625);
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// Max normalized value.
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try testing.expectEqual(try parseFloat(f128, "0xf.fffffffffffffffffffffffffff8p+16380"), math.floatMax(f128));
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try testing.expectEqual(try parseFloat(f128, "-0xf.fffffffffffffffffffffffffff8p+16380"), -math.floatMax(f128));
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// Min normalized value.
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try testing.expectEqual(try parseFloat(f128, "0x1p-16382"), math.floatMin(f128));
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try testing.expectEqual(try parseFloat(f128, "-0x1p-16382"), -math.floatMin(f128));
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// Min denormalized value.
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try testing.expectEqual(try parseFloat(f128, "0x1p-16494"), math.floatTrueMin(f128));
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try testing.expectEqual(try parseFloat(f128, "-0x1p-16494"), -math.floatTrueMin(f128));
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// ensure round-to-even
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try testing.expectEqual(try parseFloat(f128, "0x1.edcb34a235253948765432134674fp-1"), 0x1.edcb34a235253948765432134674fp-1);
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}
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