#include "key.h"

void KeyInit(void)
{
	//設置引腳的輸入模式和輸出模式
	keyInputPortInputMode;
	keyInputPortPullUp;
	keyOutputPortOutputMode;
	keyOutputPortInit;

	keyMask = 0xF0;   //屏蔽碼，沒有按鍵時為0xF0
	keyValue = 0x00;  //初始化鍵值為0
	keyState = 0x00;  //初始化按鍵狀態為第0歌狀態
}
/************************************************
函數unsigned char FindKeyValue (void)用于查找鍵值
************************************************/
unsigned char FindKeyValue (void)
{
	unsigned keyReturn;    //返回的鍵值，并初始化為無鍵值
	keyReturn = 0;			

	switch (keyState)
	{
	case keyState0:
		keyOutput2 = 1;			//第二行置高電平
		keyOutput1 = 0;			//第一行置低電平，掃描第一行

		keyValue = keyInput & keyMask;	//讀取鍵值

		if(keyValue != keyMask)			//如果有鍵按下，則進入狀態1
		{
			keyState = keyState1;
		}
		else							//否則第一行置高電平，第二行置低電平，掃描第二行
		{
			keyOutput1 = 1;
			keyOutput2 = 0;
			keyValue = keyInput & keyMask;   //讀取鍵值

			if(keyValue != keyMask)			//如果有鍵按下，則進入狀態1
			{
				keyState = keyState1;
			}
			else							//否則第二行也置高電平
			{
				keyOutput2 = 1;
			}

		}

		break;
		
	case keyState1:

		if (keyValue == (keyInput & keyMask))	//如果讀取的按鍵值和上次一樣，則進入狀態2，并判斷按鍵，否則進入狀態0
		{
			keyState = keyState2;

			if (keyOutput1)
			{
				switch(keyValue)
				{
				case 0b11100000:
					keyReturn = key1;
					break;

				case 0b11010000:
					keyReturn = key2;
					break;

				case 0b10110000:
					keyReturn = key3;
					break;

				case 0b01110000:
					keyReturn = key4;
					break;

				};

			}
			else
			{
				switch(keyValue)
				{
				case 0b11100000:
					keyReturn = key5;
					break;

				case 0b11010000:
					keyReturn = key6;
					break;

				case 0b10110000:
					keyReturn = key7;
					break;

				case 0b01110000:
					keyReturn = key8;
					break;

				};
			}

		}
		else
		{
			keyState = keyState0;
		}

		break;

	case keyState2:         //狀態2中判斷按鍵是否已經釋放，如果已經釋放則返回狀態0
		
		keyOutput1 = 0;
		keyOutput2 = 0;

		if ((keyInput & keyMask) == keyMask)
		{
			keyState = keyState0;
		}

		break;
		
	};
	
	return keyReturn;//返回讀取的鍵值
}