xmdstub.s

<基于fpga的嵌入式设计上的光盘的第四章第二个实验

	/*--------------------------------------------------*/
SingleStep:
	brlid r15, Get_All_Registers
	nop
	rtsd r16, 0
	lwi r15,r0,register_dump+15*4

	/*--------------------------------------------------*/	
	/* When Processor resets                            */
	/*   - save all registers to the register_dump      */
	/*   - send 0x3 ('Processor reset') to host         */
	/*   - Jump to the main command entry code          */
	/*--------------------------------------------------*/	
	
StartUp_Entry:
	swi r15,r0,register_dump+60
	brid Dump_All_Registers
	ori r15,r0,ProcReset_signal
	/* Control goes to SendStatus from DumpAllRegisters */
	
	
	/*--------------------------------------------------*/	
	/* Program End entry                                */
	/* When control returns from the program or         */
	/* on exit()                                        */
	/*   - save all register to the register_dump       */
	/*   - send 0x0 ('Reached_End_Of_Program') to host  */
	/*   - Jump to the main command entry code          */
	/*--------------------------------------------------*/	

Program_Exit:
	swi r15,r0,register_dump+60
	brid Dump_All_Registers
	ori r15,r0,Reached_End_Of_Program
	/* Control goes to SendStatus from DumpAllRegisters */
	
	/*--------------------------------------------------*/
	/* Debug Entry code                                 */
	/* The code that breakpoint instruction will call   */
	/*  - Will save all registers                       */
	/*  - Send 0x01 to the host                         */
	/*  - Jump to the main command entry code           */
	/*--------------------------------------------------*/
Debug_Entry:
  	swi r15,r0,register_dump+60 /* Dump_All_regs doesnt do this */
	brid Dump_All_Registers
	ori r15,r0, Reached_Breakpoint
	/* Control goes to SendStatus from DumpAllRegisters */
	
	/*--------------------------------------------------*/
	/* Brk signal handler                               */
	/*  - Will save all registers                       */
	/*  - Send 0x02 to the host                         */
	/*  - Jump to the main command entry code           */
	/*--------------------------------------------------*/
Brk_Signal_Entry:
  	swi r15,r0,register_dump+60 /* Dump_All_regs doesnt do this */
	lwi r15, r0, uart_stat
	andi r15,r15, Intr_Enabled
	ori r15, r15, Clear_ExtBreak
	swi r15, r0, uart_ctrl
	brid Dump_All_Registers
	ori r15,r0, Received_brk_signal
	/* Control goes to SendStatus from DumpAllRegisters */
	

	/*  Send the status to the host                     */
Send_Status:
	brlid r29,Wait_for_TX_space
	nop
	swi  r15,r0,uart_tx_data
	bri Wait_for_command



	/*--------------------------------------------------*/
	/* NOTE : ADDED FOR THE SAKE OF COMPATIBILITY WITH MDK 2.2 */
	/* Return Debug Address Entry command               */
	/* The code will return the address for the         */
	/* Debug_Entry code section as four bytes           */
	/*--------------------------------------------------*/
Return_Dbg_Addr:
	brlid r15,Send_32Bit
	addi r5,r0,Debug_Entry
	bri Wait_for_command


/*--------------------------------------------------*/
/* Low Level Helper routines                        */	
/*--------------------------------------------------*/	


	/*--------------------------------------------------*/
	/* Get a byte function                              */
	/*  - loop until a character has been received      */
	/*  - read the character                            */
	/* Uses: R3                                         */
	/* Parameters: None                                 */
	/* Returns using R27                                */
	/* Result in: R3                                    */
	/*--------------------------------------------------*/
Get_Byte:	
	/* Get 1 byte and return it in r3 */
	lwi  r3,r0,uart_stat
	andi r3,r3,uart_rx_data_valid     /* rx data present */
	beqi r3, Get_Byte
	lwi  r3,r0,uart_rx_data
	rtsd r27,8
	nop
	
	/*--------------------------------------------------*/
	/* Get a char function                              */
	/*  - Get a byte from the UART                      */
	/*  - Check if it's an escape character             */
	/*  - if it is                                      */
	/* Uses: R3, R26, R27                               */
	/* Parameters: None                                 */
	/* Returns using R29                                */
	/* Result in: R3                                    */
	/*--------------------------------------------------*/
Get_Char:	
	brlid r27,Get_Byte
	nop
	xori r26,r3,Escape_Char
	bnei r26,No_Escape
	brlid r27,Get_Byte
	nop
Get_Char_Return:		
	rtsd r29,8
	nop
No_Escape:	
	xori r26,r3,ReSync_Char
	beqi r26,ReSync
	bri Get_Char_Return

	/*--------------------------------------------------*/
	/* Get a half word function                         */
	/*  - Get 2 bytes using Get_Char function           */
	/*  - Store each byte in a memory location,temp_mem */
	/*    using store byte SBI instruction              */
	/*    stores the received byte in the order         */
	/*    addr+1,addr+0			            */
	/* Uses: R3,R29,R30,R31                             */
	/* Parameters: None                                 */
	/* Returns using R15                                */
	/* Result in: R3                                    */
	/*--------------------------------------------------*/	
Get_16Bit:
	and  r30,r0,r0
	addi r31,r0,1
Get_16Bit_1:
	/* Get the next byte */
	brlid r29,Get_Char
	nop
	sbi r3,r31,temp_mem
	addi r31,r31,-1
	bgei r31,Get_16Bit_1
	rtsd r15,8
	lhui r3,r0,temp_mem	
				
	/*--------------------------------------------------*/
	/* Get a word function                              */
	/*  - Get 4 bytes using Get_Char function           */
	/*  - Store each byte in a memory location,temp_mem */
	/*    using store byte SBI instruction              */
	/*    stores the received byte in the order         */
	/*    addr+3,addr+2,addr+1,addr+0                   */
	/* Uses: R3,R29,R30,R31                             */
	/* Parameters: None                                 */
	/* Returns using R15                                */
	/* Result in: R3                                    */
	/*--------------------------------------------------*/
Get_32Bit:
	and  r30,r0,r0
	addi r31,r0,3
Get_32Bit_1:
	/* Get the next byte */
	brlid r29,Get_Char
	nop
	sbi r3,r31,temp_mem
	addi r31,r31,-1
	bgei r31,Get_32Bit_1
	rtsd r15,8
	lwi r3,r0,temp_mem


	/*--------------------------------------------------*/
	/* Wait for UART TX is become empty function        */
	/*  - loop until UART TXC buffer is empty           */
	/* Uses: R25                                        */
	/* Parameters: None                                 */
	/* Returns using R29                                */
	/* Result in: no result                             */
	/*--------------------------------------------------*/
Wait_for_TX_space:
	lwi  r25,r0,uart_stat
	andi r25,r25,uart_tx_buffer_empty   /* tx buffer empty */
	beqi r25, Wait_for_TX_space
	rtsd r29,8
	nop

	/*--------------------------------------------------*/
	/* Send a half word function                        */
	/*  - Store the half word to send in temp_mem       */
	/*  - loop                                          */
	/*     - Wait for TX to become empty                */
	/*     - Read a byte out of temp_mem                */
	/*       reads the bytes in the order               */
	/*       addr+1,addr+0			            */
	/*     - Send that byte (Write to the UART_TX fifo) */
	/*     - Repeat for all 2 bytes                     */ 
	/* Uses: R3,R25,R29,R30,R31                         */
	/* Parameters: R5 Half Word to send                 */
	/* Returns using R15                                */
	/* Result in: No result                             */
	/*--------------------------------------------------*/
Send_16Bit:	
	addi r31,r0,1
	brid Send_32Bit_1
	shi r5,r0,temp_mem
	
	/*--------------------------------------------------*/
	/* Send a word function                             */
	/*  - Store the word to send in temp_mem            */
	/*  - loop                                          */
	/*     - Wait for TX to become empty                */
	/*     - Read a byte out of temp_mem                */
	/*       reads the bytes in the order               */
	/*       addr+3,addr+2,addr+1,addr+0                */
	/*     - Send that byte (Write to the UART_TX fifo) */
	/*     - Repeat for all 4 bytes                     */ 
	/* Uses: R3,R25,R29,R30,R31                         */
	/* Parameters: R5 Word to send                      */
	/* Returns using R15                                */
	/* Result in: No result                             */
	/*--------------------------------------------------*/
Send_32Bit:
	addi r31,r0,3
	swi r5,r0,temp_mem
	
Send_32Bit_1:	
	/* Wait for free space in the transmit buffer */
	brlid r29, Wait_for_TX_space

	/* Get the right byte from the word to transmit */
	lbui r30,r31,temp_mem
	swi  r30,r0,uart_tx_data 

	addi r31,r31,-1
	bgei r31, Send_32Bit_1

	rtsd r15,8
	nop

	/*--------------------------------------------------*/
	/* Save register to register_dump function          */
	/*  - Store all registers to the register dump      */
	/*    except R0  : makes no sense always zero       */
	/*           R15 : needed for the return address    */
	/*  - R15 has to saved before calling this function */
	/*    to the address register_dump+15*4             */
	/* Uses:                                            */
	/* Parameters:                                      */
	/* Returns using R15                                */
	/* Result in: No result                             */
	/*--------------------------------------------------*/
Dump_All_Registers:
/*	swi r0,r0,register_dump + 0 */
	swi r1,r0,register_dump + 4
	swi r2,r0,register_dump + 8
	swi r3,r0,register_dump+12
	swi r4,r0,register_dump+16
	swi r5,r0,register_dump+20
	swi r6,r0,register_dump+24
	swi r7,r0,register_dump+28
	swi r8,r0,register_dump+32
	swi r9,r0,register_dump+36
	swi r10,r0,register_dump+40
	swi r11,r0,register_dump+44
	swi r12,r0,register_dump+48
	swi r13,r0,register_dump+52
	swi r14,r0,register_dump+56
/*  	swi r15,r0,register_dump+60 */
	swi r16,r0,register_dump+64
	swi r17,r0,register_dump+68
	swi r18,r0,register_dump+72
	swi r19,r0,register_dump+76
	swi r20,r0,register_dump+80
	swi r21,r0,register_dump+84
	swi r22,r0,register_dump+88
	swi r23,r0,register_dump+92
	swi r24,r0,register_dump+96
	swi r25,r0,register_dump+100
	swi r26,r0,register_dump+104
	swi r27,r0,register_dump+108
	swi r28,r0,register_dump+112
	swi r29,r0,register_dump+116
	swi r30,r0,register_dump+120
	swi r31,r0,register_dump+124
	mfs r31, rmsr
	brid Send_Status
	swi r31,r0,register_dump+132

	/*--------------------------------------------------*/
	/* Read registers from register_dump function       */
	/*  - Read all registers to the register dump       */
	/*    except R0  : makes no sense always zero       */
	/*           R15 : needed for the return address    */
	/*           R16 : contains the debug return address*/
	/*                 and can't be overwritten         */
	/*           R29 : is used by the eXecute command   */
	/*                 for storing the execution address*/
	/* Uses:                                            */
	/* Parameters:                                      */
	/* Returns using R15                                */
	/* Result in: No result                             */
	/*--------------------------------------------------*/
Get_All_Registers:	
	/* lwi r0,r0,register_dump + 0 */
	lwi r1,r0,register_dump + 4
	lwi r2,r0,register_dump + 8
	lwi r3,r0,register_dump+12
	lwi r4,r0,register_dump+16
	lwi r5,r0,register_dump+20
	lwi r6,r0,register_dump+24
	lwi r7,r0,register_dump+28
	lwi r8,r0,register_dump+32
	lwi r9,r0,register_dump+36
	lwi r10,r0,register_dump+40
	lwi r11,r0,register_dump+44
	lwi r12,r0,register_dump+48
	lwi r13,r0,register_dump+52
	lwi r14,r0,register_dump+56
	/* lwi r15,r0,register_dump+60 */
	lwi r16,r0,register_dump+64
	lwi r17,r0,register_dump+68
	lwi r18,r0,register_dump+72
	lwi r19,r0,register_dump+76
	lwi r20,r0,register_dump+80
	lwi r21,r0,register_dump+84
	lwi r22,r0,register_dump+88
	lwi r23,r0,register_dump+92
	lwi r24,r0,register_dump+96
	lwi r25,r0,register_dump+100
	lwi r26,r0,register_dump+104
	lwi r27,r0,register_dump+108
	lwi r28,r0,register_dump+112
	lwi r29,r0,register_dump+116
	lwi r30,r0,register_dump+120
	lwi r31,r0,register_dump+132
	mts rmsr, r31
	rtsd r15,8
	lwi r31,r0,register_dump+124
	
	/* Temporary memory needed for the byte-to-word */
	/* and word-to-byte translation                 */
	.data
	.align 2
temp_mem:			
	.int 0

	/* 34 words containing the register_dump (32 regs + pc + msr)       */
	.align 2
register_dump:
	.fill 34, 4, 0

	.end	xmd_stub