Initial Commit

README.md

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+# iossimdjson
+Experimenting with JSON decoding on ios 
+
+## Requirements
+
+- A recent mac with Xcode installed
+- A recent iOS device
+
+
+## Usage
+
+- Open BitmapDecoding.xcodeproj in Xcode (macOS) 
+- Click on the "BitmapDecoding" project within Xcode, go to "Identity" and select a valid account under "Team".
+- Plug your device (e.g., iPhone) in your mac.
+- In Xcode, go to Window > Devices. This will open a new window. You should see your device in this new window. Don't lose this new window.
+- In Xcode, go to Product > Build For > Running
+- You should see in Xcode under Products "BitmapDecoding.app", drag and drop it into the "Devices" window we opened previously.
+- You should now see the app on your device. By default, iOS won't let you run it, so go under Settings > General. You will find a setting there to allow you to run the app.
+- Run the app.
+
+## Sample result
+
+iPhone XR, Xcode 10.1
+```
+129996 129996 
+basic_decoder time 49.067215 nanoseconds per set bit 
+simdjson_decoder time 11.251628  nanoseconds per set bit  
+129996 129996 
+basic_decoder time 1.704219 nanoseconds per set bit 
+simdjson_decoder time 1.197152  nanoseconds per set bit  
+129996 129996 
+basic_decoder time 1.682744 nanoseconds per set bit 
+simdjson_decoder time 1.172792  nanoseconds per set bit  
+129996 129996 
+basic_decoder time 1.693321 nanoseconds per set bit 
+simdjson_decoder time 1.175998  nanoseconds per set bit  
+129996 129996 
+basic_decoder time 1.683385 nanoseconds per set bit 
+simdjson_decoder time 1.168626  nanoseconds per set bit  
+129996 129996 
+basic_decoder time 1.699411 nanoseconds per set bit 
+simdjson_decoder time 1.176318  nanoseconds per set bit  
+129996 129996 
+basic_decoder time 1.750374 nanoseconds per set bit 
+simdjson_decoder time 1.171510  nanoseconds per set bit  
+129996 129996 
+basic_decoder time 1.744284 nanoseconds per set bit 
+simdjson_decoder time 1.167344  nanoseconds per set bit  
+129996 129996 
+basic_decoder time 1.717040 nanoseconds per set bit 
+simdjson_decoder time 1.164138  nanoseconds per set bit  
+129996 129996 
+basic_decoder time 1.792363 nanoseconds per set bit 
+simdjson_decoder time 1.331451  nanoseconds per set bit  
+
+```
+
+The Apple A12 has seemingly a rated frequency of 2.5GHz. So these nanoseconds translate into about 4.3 and 3.0 cycles per set bit. For comparison, an Intel Skylake get 4.7	and	3.4 cycles per set bit.
+
+
+
+## Credit
+
+
+The app. reuses code by Benoît Maison.