iqconvert: converts from u8 to f32 without issuesmain

1 files changed, 88 insertions, 0 deletions

diff --git a/IQ/IQUtils.swift b/IQ/IQUtils.swift
new file mode 100644
index 0000000..9d1b048
--- /dev/null
+++ b/IQ/IQUtils.swift
@@ -0,0 +1,88 @@
+//
+//  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
+}