const std = @import("std");
pub fn BiasedFp(comptime T: type) type {
const MantissaT = mantissaType(T);
return struct {
const Self = @This();
f: MantissaT,
e: i32,
pub fn zero() Self {
return .{ .f = 0, .e = 0 };
}
pub fn zeroPow2(e: i32) Self {
return .{ .f = 0, .e = e };
}
pub fn inf(comptime FloatT: type) Self {
return .{ .f = 0, .e = (1 << std.math.floatExponentBits(FloatT)) - 1 };
}
pub fn eql(self: Self, other: Self) bool {
return self.f == other.f and self.e == other.e;
}
pub fn toFloat(self: Self, comptime FloatT: type, negative: bool) FloatT {
var word = self.f;
word |= @intCast(MantissaT, self.e) << std.math.floatMantissaBits(FloatT);
var f = floatFromUnsigned(FloatT, MantissaT, word);
if (negative) f = -f;
return f;
}
};
}
pub fn floatFromUnsigned(comptime T: type, comptime MantissaT: type, v: MantissaT) T {
return switch (T) {
f16 => @bitCast(f16, @truncate(u16, v)),
f32 => @bitCast(f32, @truncate(u32, v)),
f64 => @bitCast(f64, @truncate(u64, v)),
f128 => @bitCast(f128, v),
else => unreachable,
};
}
pub fn Number(comptime T: type) type {
return struct {
exponent: i64,
mantissa: mantissaType(T),
negative: bool,
many_digits: bool,
hex: bool,
};
}
pub fn isEightDigits(v: u64) bool {
const a = v +% 0x4646_4646_4646_4646;
const b = v -% 0x3030_3030_3030_3030;
return ((a | b) & 0x8080_8080_8080_8080) == 0;
}
pub fn isDigit(c: u8, comptime base: u8) bool {
std.debug.assert(base == 10 or base == 16);
return if (base == 10)
'0' <= c and c <= '9'
else
'0' <= c and c <= '9' or 'a' <= c and c <= 'f' or 'A' <= c and c <= 'F';
}
pub fn mantissaType(comptime T: type) type {
return switch (T) {
f16, f32, f64 => u64,
f128 => u128,
else => unreachable,
};
}