const std = @import("../../std.zig");
const debug = std.debug;
const math = std.math;
const testing = std.testing;
const cmath = math.complex;
const Complex = cmath.Complex;
pub fn ldexp_cexp(z: anytype, expt: i32) @TypeOf(z) {
    const T = @TypeOf(z.re);
    return switch (T) {
        f32 => ldexp_cexp32(z, expt),
        f64 => ldexp_cexp64(z, expt),
        else => unreachable,
    };
}
fn frexp_exp32(x: f32, expt: *i32) f32 {
    const k = 235; 
    const kln2 = 162.88958740; 
    const exp_x = @exp(x - kln2);
    const hx = @bitCast(u32, exp_x);
    
    expt.* = @intCast(i32, hx >> 23) - (0x7f + 127) + k;
    return @bitCast(f32, (hx & 0x7fffff) | ((0x7f + 127) << 23));
}
fn ldexp_cexp32(z: Complex(f32), expt: i32) Complex(f32) {
    var ex_expt: i32 = undefined;
    const exp_x = frexp_exp32(z.re, &ex_expt);
    const exptf = expt + ex_expt;
    const half_expt1 = @divTrunc(exptf, 2);
    const scale1 = @bitCast(f32, (0x7f + half_expt1) << 23);
    const half_expt2 = exptf - half_expt1;
    const scale2 = @bitCast(f32, (0x7f + half_expt2) << 23);
    return Complex(f32).init(
        @cos(z.im) * exp_x * scale1 * scale2,
        @sin(z.im) * exp_x * scale1 * scale2,
    );
}
fn frexp_exp64(x: f64, expt: *i32) f64 {
    const k = 1799; 
    const kln2 = 1246.97177782734161156; 
    const exp_x = @exp(x - kln2);
    const fx = @bitCast(u64, exp_x);
    const hx = @intCast(u32, fx >> 32);
    const lx = @truncate(u32, fx);
    expt.* = @intCast(i32, hx >> 20) - (0x3ff + 1023) + k;
    const high_word = (hx & 0xfffff) | ((0x3ff + 1023) << 20);
    return @bitCast(f64, (@as(u64, high_word) << 32) | lx);
}
fn ldexp_cexp64(z: Complex(f64), expt: i32) Complex(f64) {
    var ex_expt: i32 = undefined;
    const exp_x = frexp_exp64(z.re, &ex_expt);
    const exptf = @as(i64, expt + ex_expt);
    const half_expt1 = @divTrunc(exptf, 2);
    const scale1 = @bitCast(f64, (0x3ff + half_expt1) << (20 + 32));
    const half_expt2 = exptf - half_expt1;
    const scale2 = @bitCast(f64, (0x3ff + half_expt2) << (20 + 32));
    return Complex(f64).init(
        @cos(z.im) * exp_x * scale1 * scale2,
        @sin(z.im) * exp_x * scale1 * scale2,
    );
}