.text 
.global _start
_start: 

		/* 使能GPIOE、GPIOF寄存器   RCC_MP_AHB4ENSETR 
		 * 基地址: 0x50000000 + 偏移地址: 0xA28 = 0x50000A28
		 * RCC_MP_AHB4ENSETR[4]->1	RCC_MP_AHB4ENSETR[5]->1
		 */	
		
		LDR R0,=0x50000A28
		LDR R1,[R0]
		ORR R1,R1,#(0x1<<4)
		STR R1,[R0]
		
		LDR R0,=0x50000A28
		LDR R1,[R0]
		ORR R1,R1,#(0x1<<5)
		STR R1,[R0]
		
		/* 设置PE10,PE8,PF10引脚为输出模式
		 * GPIOF基地址: 0x50007000 + 偏移地址: 0x00 = 0x50007000
		 * GPIOE基地址: 0x50006000 + 偏移地址: 0x00 = 0x50006000
		 * PE10: GPIOE_MODER[21:20]->01
		 * PF10: GPIOF_MODER[21:20]->01
		 * PE8:  GPIOE_MODER[17:16]->01
		 */
		
		LDR R0, =0x50007000
		LDR R1,[R0]
		BIC R1,R1,#(0x3<<20)
		ORR R1,R1,#(0x1<<20)
		STR R1,[R0]
		
		LDR R0, =0x50006000
		LDR R1,[R0]
		BIC R1,R1,#(0x3<<20)
		ORR R1,R1,#(0x1<<20)
		STR R1,[R0]
		
		LDR R0, =0x50006000
		LDR R1,[R0]
		BIC R1,R1,#(0x3<<16)
		ORR R1,R1,#(0x1<<16)
		STR R1,[R0]
		
		/* 设置PE10,PE8,PF10引脚为推挽输出
  		 * GPIOF基地址: 0x50007000 + 偏移地址: 0x04 = 0x50007004
		 * GPIOE基地址: 0x50006000 + 偏移地址: 0x04 = 0x50006004
		 * GPIOE_OTYPER[10]->0
		 * GPIOF_OTYPER[10]->0
		 * GPIOE_OTYPER[8]->0
		 */
		
		LDR R0,=0x50007004
		LDR R1,[R0]
		BIC R1,R1,#(0x1<<10)
		STR R1,[R0]
		
		LDR R0,=0x50006004
		LDR R1,[R0]
		BIC R1,R1,#(0x1<<10)
		STR R1,[R0]
		
		LDR R0,=0x50006004
		LDR R1,[R0]
		BIC R1,R1,#(0x1<<8)
		STR R1,[R0]
		
		/* 设置PE10,PE8,PF10引脚为低速输出
  		 * GPIOF基地址: 0x50007000 + 偏移地址: 0x08 = 0x50007008
		 * GPIOE基地址: 0x50006000 + 偏移地址: 0x08 = 0x50006008
		 * GPIOE_OSPEEDR[21:20]->00
		 * GPIOF_OSPEEDR[21:20]->00
		 * GPIOE_OSPEEDR[17:16]->00
		 */
		
		LDR R0,=0x50007008
		LDR R1,[R0]
		BIC R1,R1,#(0x3<<20)
		STR R1,[R0]
		
		LDR R0,=0x50006008
		LDR R1,[R0]
		BIC R1,R1,#(0x3<<20)
		STR R1,[R0]
		
		LDR R0,=0x50006008
		LDR R1,[R0]
		BIC R1,R1,#(0x3<<16)
		STR R1,[R0]
		
		/* 设置PE10,PE8,PF10引脚没有上下拉电阻
  		 * GPIOF基地址: 0x50007000 + 偏移地址: 0x0C = 0x5000700C
		 * GPIOE基地址: 0x50006000 + 偏移地址: 0x0C = 0x5000600C
		 * GPIOE_PUPDR[21:20]->00
		 * GPIOF_PUPDR[21:20]->00
		 * GPIOE_PUPDR[17:16]->00
		 */
		 
		LDR R0,=0x5000700C
		LDR R1,[R0]
		BIC R1,R1,#(0x3<<20)
		STR R1,[R0] 
		
		LDR R0,=0x5000600C
		LDR R1,[R0]
		BIC R1,R1,#(0x3<<20)
		STR R1,[R0]

		LDR R0,=0x5000600C
		LDR R1,[R0]
		BIC R1,R1,#(0x3<<16)
		STR R1,[R0]


		/* 设置PE10,PE8,PF10实现流水灯
  		 * GPIOF基地址: 0x50007000 + 偏移地址: 0x14 = 0x50007014
		 * GPIOE基地址: 0x50006000 + 偏移地址: 0x14 = 0x50006014
		 * GPIOE_ODR[10]->1
		 * GPIOF_ODR[10]->1
		 * GPIOE_ODR[8]->1
		 */
loop:

		LDR R0,=0X50006014
		LDR R1,[R0]
		ORR R1,R1,#(0x1<<10)
		STR R1,[R0]
		BL delay

		LDR R0,=0X50006014
		LDR R1,[R0]
		BIC R1,R1,#(0x1<<10)
		STR R1,[R0]
		BL delay
		
		LDR R0,=0X50007014
		LDR R1,[R0]
		ORR R1,R1,#(0x1<<10)
		STR R1,[R0]
		BL delay

		LDR R0,=0X50007014
		LDR R1,[R0]
		BIC R1,R1,#(0x1<<10)
		STR R1,[R0]
		BL delay
		
		LDR R0,=0X50006014
		LDR R1,[R0]
		ORR R1,R1,#(0x1<<8)
		STR R1,[R0]
		BL delay

		LDR R0,=0X50006014
		LDR R1,[R0]
		BIC R1,R1,#(0x1<<8)
		STR R1,[R0]
		BL delay
		
		
b loop



		/* 延时函数 */

delay:
		LDR R4,=0X1000000
mm:
		CMP R4,#0
		SUBNE R4,R4,#1
		BNE mm
		MOV PC,LR

.end