11-3.md

Code: Part of Keyboard.[c, h] that converts scan code to ascii code

/*
 *  Because newly added code is really long, It looks ugly to paste here.
 *  execute git diff on Keyboard.c and h
 */

/* newly added structures and functions:
 *   kKeyMappingEntryStruct (structure that maps scan code to ascii)
 *   kKeyboardManagerStruct (structure that saves current keyboard state)
 * 
 *   gs_stKeyboardManager (global singleton of kKeyboardManagerStruct)
 *   gs_vstKeyMappingTable (table that maps scan code to ascii)
 *  
 *   Below functions are related to kKeyboardManagerStruct
 *   kShouldUseCombinedCode (private)
 *   kIsAlphabetScanCode (private)
 *   kIsNumberOrSymbolScanCode (private)
 *   kIsNumberPadScanCode (private)
 *   updateCombinationKeyStatusAndLED (private)
 * 
 *   kConvertScanCodeToASCIICode (public)
 */ 

Explanation

Scan Code

1. Most scan code is 1 byte

2. Extended scan code is 2 bytes and they start with 0xE0

3. A unique key, pause, is extended scan code whose size is 3 bytes and starts with 0xE1

4. Released key scan code has bit 7 set

keyboard scan code part 1

keyboard scan code part 2

keyboard related function explanation