SugarDS is an Amstrad CPC emulator for Nintendo DS and DSi by Nige Rideout. This version 1.4 features :

• DSi now double-buffers LCD rendering for smoother performance and syncs to true 50Hz refresh
• Added Favorites system - use SELECT when loading games to toggle between like/love
• Added new 130% rendering speed as a per-game option
• Improved key map handling - all virtual Amstrad CPC keys are now mappable to the NDS keys
• Added vertical jitter handling - improves look of vertical compression making games like Tempest look much improved when scaled
• Improved save state support - AY music is properly restored when loading an old save state
• Added instructions for use on first boot of the emulator
• Switched to O3 optimization for a few more frames of performance
• Lots of other small improvements and cleanups under the hood as time permitted

And if you are curious and you go check his Github profile, you will see that he has written several other emulators for Nintendo DS and DSi.