mirror of
https://codeberg.org/ziglang/zig.git
synced 2025-12-07 22:34:28 +00:00
d29871977f
We already have a LICENSE file that covers the Zig Standard Library. We no longer need to remind everyone that the license is MIT in every single file. Previously this was introduced to clarify the situation for a fork of Zig that made Zig's LICENSE file harder to find, and replaced it with their own license that required annual payments to their company. However that fork now appears to be dead. So there is no need to reinforce the copyright notice in every single file.
58 lines
1.9 KiB
Zig
58 lines
1.9 KiB
Zig
const builtin = @import("builtin");
|
|
const std = @import("std");
|
|
const maxInt = std.math.maxInt;
|
|
|
|
const significandBits = 23;
|
|
const exponentBias = 127;
|
|
const implicitBit = @as(u32, 1) << significandBits;
|
|
|
|
pub fn __floatunsisf(arg: u32) callconv(.C) f32 {
|
|
@setRuntimeSafety(builtin.is_test);
|
|
|
|
if (arg == 0) return 0.0;
|
|
|
|
// The exponent is the width of abs(a)
|
|
const exp = @as(u32, 31) - @clz(u32, arg);
|
|
|
|
var mantissa: u32 = undefined;
|
|
if (exp <= significandBits) {
|
|
// Shift a into the significand field and clear the implicit bit
|
|
const shift = @intCast(u5, significandBits - exp);
|
|
mantissa = @as(u32, arg) << shift ^ implicitBit;
|
|
} else {
|
|
const shift = @intCast(u5, exp - significandBits);
|
|
// Round to the nearest number after truncation
|
|
mantissa = @as(u32, arg) >> shift ^ implicitBit;
|
|
// Align to the left and check if the truncated part is halfway over
|
|
const round = arg << @intCast(u5, 31 - shift);
|
|
mantissa += @boolToInt(round > 0x80000000);
|
|
// Tie to even
|
|
mantissa += mantissa & 1;
|
|
}
|
|
|
|
// Use the addition instead of a or since we may have a carry from the
|
|
// mantissa to the exponent
|
|
var result = mantissa;
|
|
result += (exp + exponentBias) << significandBits;
|
|
|
|
return @bitCast(f32, result);
|
|
}
|
|
|
|
pub fn __aeabi_ui2f(arg: u32) callconv(.AAPCS) f32 {
|
|
@setRuntimeSafety(false);
|
|
return @call(.{ .modifier = .always_inline }, __floatunsisf, .{arg});
|
|
}
|
|
|
|
fn test_one_floatunsisf(a: u32, expected: u32) !void {
|
|
const r = __floatunsisf(a);
|
|
try std.testing.expect(@bitCast(u32, r) == expected);
|
|
}
|
|
|
|
test "floatunsisf" {
|
|
// Test the produced bit pattern
|
|
try test_one_floatunsisf(0, 0);
|
|
try test_one_floatunsisf(1, 0x3f800000);
|
|
try test_one_floatunsisf(0x7FFFFFFF, 0x4f000000);
|
|
try test_one_floatunsisf(0x80000000, 0x4f000000);
|
|
try test_one_floatunsisf(0xFFFFFFFF, 0x4f800000);
|
|
}
|