//
//  IQUtils.swift
//  PrySDR
//
//  Created by Jacky Jack on 21/01/2025.
//

import Accelerate

/// Convert from UInt8 to Float, naive implementation
/// - Parameters:
///   - arr: array of UInt8
/// - Returns: Return floats -0.996...0.996
///
func cnvU8toFloat32(_ arr: [UInt8]) -> [Float32] {
    
    //let iq = IQ(size: 8, bits: 8, sign: false, complex: true)
    
    var out: [Float32] = .init(repeating: 0.0, count: arr.count)
    
    // 0..255 -> -0.996 ... 0.996
    // 0..127 -> -0.996 ... 0.0039
    // 128...255 -> 0.0039 ... 0.996
    for i in 0..<arr.count {
        /*
        if arr[i] >= 128 {
            out[i] = Float(arr[i]-128)/128.0
        } else { //
            out[i] = Float(Int(arr[i])-128)/128.0
        }*/
        out[i] = (Float(arr[i])-127.5)/128.0
    }
    
    return out
}

/// Convert from UInt8 to Float, naive implementation rtlsdr specfic
/// https://cgit.osmocom.org/gr-osmosdr/tree/lib/rtl/rtl_source_c.cc#n179
/// - Parameters:
///   - arr: array of UInt8
/// - Returns: Return floats -0.996...0.996
///
func cnvU8toFloat32_rtlsdr(_ arr: [UInt8]) -> [Float32] {
    
    //let iq = IQ(size: 8, bits: 8, sign: false, complex: true)
    
    var out: [Float32] = .init(repeating: 0.0, count: arr.count)
    
    // 0..255 -> -1.0 ... 1.0
    for i in 0..<arr.count {
        /*
        if arr[i] >= 128 {
            out[i] = Float(arr[i]-128)/128.0
        } else { //
            out[i] = Float(Int(arr[i])-128)/128.0
        }*/
        out[i] = (Float(arr[i])-127.4)/128.0
    }
    
    return out
}


/// Convert from UInt8 to Float, using Accel framework
/// - Parameters:
///   - arr: array of UInt8
/// - Returns: Return floats -1.0...1.0
///
func cnvU8toFloat32_accel(_ arr: [UInt8]) -> [Float32] {
    var out: [Float32] = .init(repeating: 0.0, count: arr.count)
    vDSP.convertElements(of: arr, to: &out)
    out = vDSP.add(-127.5, out)
    out = vDSP.divide(out, 128)
    return out
}

/// Convert from UInt8 to Float, using Accel framework specific to rtlsdr
/// - Parameters:
///   - arr: array of UInt8
/// - Returns: Return floats -1.0...1.0
///
func cnvU8toFloat32_accel_rtlsdr(_ arr: [UInt8]) -> [Float32] {
    var out: [Float32] = .init(repeating: 0.0, count: arr.count)
    vDSP.convertElements(of: arr, to: &out)
    out = vDSP.add(-127.4, out)
    out = vDSP.divide(out, 128)
    return out
}