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			360 lines
		
	
	
		
			9.3 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
			
		
		
	
	
			360 lines
		
	
	
		
			9.3 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
| // Copyright 2015-2016 Espressif Systems (Shanghai) PTE LTD
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| //
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| // Licensed under the Apache License, Version 2.0 (the "License");
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| // you may not use this file except in compliance with the License.
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| // You may obtain a copy of the License at
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| 
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| //     http://www.apache.org/licenses/LICENSE-2.0
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| //
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| // Unless required by applicable law or agreed to in writing, software
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| // distributed under the License is distributed on an "AS IS" BASIS,
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| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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| // See the License for the specific language governing permissions and
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| // limitations under the License.
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| 
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| /******************************************************************************
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|  * Description: A stub to make the ESP32 debuggable by GDB over the serial 
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|  * port, at least enough to do a backtrace on panic. This gdbstub is read-only:
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|  * it allows inspecting the ESP32 state 
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|  *******************************************************************************/
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| 
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| #include "rom/ets_sys.h"
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| #include "soc/uart_reg.h"
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| #include "soc/io_mux_reg.h"
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| #include "esp_gdbstub.h"
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| #include "driver/gpio.h"
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| 
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| //Length of buffer used to reserve GDB commands. Has to be at least able to fit the G command, which
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| //implies a minimum size of about 320 bytes.
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| #define PBUFLEN 512
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| 
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| static unsigned char cmd[PBUFLEN];		//GDB command input buffer
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| static char chsum;						//Running checksum of the output packet
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| 
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| #define ATTR_GDBFN
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| 
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| //Receive a char from the uart. Uses polling and feeds the watchdog.
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| static int ATTR_GDBFN gdbRecvChar() {
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| 	int i;
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| 	while (((READ_PERI_REG(UART_STATUS_REG(0))>>UART_RXFIFO_CNT_S)&UART_RXFIFO_CNT)==0) ;
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| 	i=READ_PERI_REG(UART_FIFO_REG(0));
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| 	return i;
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| }
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| 
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| //Send a char to the uart.
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| static void ATTR_GDBFN gdbSendChar(char c) {
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| 	while (((READ_PERI_REG(UART_STATUS_REG(0))>>UART_TXFIFO_CNT_S)&UART_TXFIFO_CNT)>=126) ;
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| 	WRITE_PERI_REG(UART_FIFO_REG(0), c);
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| }
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| 
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| //Send the start of a packet; reset checksum calculation.
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| static void ATTR_GDBFN gdbPacketStart() {
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| 	chsum=0;
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| 	gdbSendChar('$');
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| }
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| 
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| //Send a char as part of a packet
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| static void ATTR_GDBFN gdbPacketChar(char c) {
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| 	if (c=='#' || c=='$' || c=='}' || c=='*') {
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| 		gdbSendChar('}');
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| 		gdbSendChar(c^0x20);
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| 		chsum+=(c^0x20)+'}';
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| 	} else {
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| 		gdbSendChar(c);
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| 		chsum+=c;
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| 	}
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| }
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| 
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| //Send a string as part of a packet
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| static void ATTR_GDBFN gdbPacketStr(const char *c) {
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| 	while (*c!=0) {
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| 		gdbPacketChar(*c);
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| 		c++;
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| 	}
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| }
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| 
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| //Send a hex val as part of a packet. 'bits'/4 dictates the number of hex chars sent.
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| static void ATTR_GDBFN gdbPacketHex(int val, int bits) {
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| 	char hexChars[]="0123456789abcdef";
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| 	int i;
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| 	for (i=bits; i>0; i-=4) {
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| 		gdbPacketChar(hexChars[(val>>(i-4))&0xf]);
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| 	}
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| }
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| 
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| //Finish sending a packet.
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| static void ATTR_GDBFN gdbPacketEnd() {
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| 	gdbSendChar('#');
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| 	gdbPacketHex(chsum, 8);
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| }
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| 
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| //Error states used by the routines that grab stuff from the incoming gdb packet
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| #define ST_ENDPACKET -1
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| #define ST_ERR -2
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| #define ST_OK -3
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| #define ST_CONT -4
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| 
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| //Grab a hex value from the gdb packet. Ptr will get positioned on the end
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| //of the hex string, as far as the routine has read into it. Bits/4 indicates
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| //the max amount of hex chars it gobbles up. Bits can be -1 to eat up as much
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| //hex chars as possible.
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| static long ATTR_GDBFN gdbGetHexVal(unsigned char **ptr, int bits) {
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| 	int i;
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| 	int no;
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| 	unsigned int v=0;
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| 	char c;
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| 	no=bits/4;
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| 	if (bits==-1) no=64;
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| 	for (i=0; i<no; i++) {
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| 		c=**ptr;
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| 		(*ptr)++;
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| 		if (c>='0' && c<='9') {
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| 			v<<=4;
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| 			v|=(c-'0');
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| 		} else if (c>='A' && c<='F') {
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| 			v<<=4;
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| 			v|=(c-'A')+10;
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| 		} else if (c>='a' && c<='f') {
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| 			v<<=4;
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| 			v|=(c-'a')+10;
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| 		} else if (c=='#') {
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| 			if (bits==-1) {
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| 				(*ptr)--;
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| 				return v;
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| 			}
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| 			return ST_ENDPACKET;
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| 		} else {
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| 			if (bits==-1) {
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| 				(*ptr)--;
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| 				return v;
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| 			}
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| 			return ST_ERR;
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| 		}
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| 	}
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| 	return v;
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| }
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| 
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| //Swap an int into the form gdb wants it
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| static int ATTR_GDBFN iswap(int i) {
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| 	int r;
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| 	r=((i>>24)&0xff);
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| 	r|=((i>>16)&0xff)<<8;
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| 	r|=((i>>8)&0xff)<<16;
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| 	r|=((i>>0)&0xff)<<24;
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| 	return r;
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| }
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| 
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| //Read a byte from ESP32 memory.
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| static unsigned char ATTR_GDBFN readbyte(unsigned int p) {
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| 	int *i=(int*)(p&(~3));
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| 	if (p<0x20000000 || p>=0x80000000) return -1;
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| 	return *i>>((p&3)*8);
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| }
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| 
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| 
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| //Register file in the format exp108 gdb port expects it.
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| //Inspired by gdb/regformats/reg-xtensa.dat
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| typedef struct {
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| 	uint32_t pc;
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| 	uint32_t a[64];
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| 	uint32_t lbeg;
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| 	uint32_t lend;
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| 	uint32_t lcount;
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| 	uint32_t sar;
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| 	uint32_t windowbase;
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| 	uint32_t windowstart;
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| 	uint32_t configid0;
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| 	uint32_t configid1;
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| 	uint32_t ps;
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| 	uint32_t threadptr;
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| 	uint32_t br;
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| 	uint32_t scompare1;
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| 	uint32_t acclo;
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| 	uint32_t acchi;
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| 	uint32_t m0;
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| 	uint32_t m1;
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| 	uint32_t m2;
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| 	uint32_t m3;
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| 	uint32_t expstate;  //I'm going to assume this is exccause...
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| 	uint32_t f64r_lo;
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| 	uint32_t f64r_hi;
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| 	uint32_t f64s;
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| 	uint32_t f[16];
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| 	uint32_t fcr;
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| 	uint32_t fsr;
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| } GdbRegFile;
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| 
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| 
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| GdbRegFile gdbRegFile;
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| 
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| /* 
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| //Register format as the Xtensa HAL has it:
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| STRUCT_FIELD (long, 4, XT_STK_EXIT,     exit)
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| STRUCT_FIELD (long, 4, XT_STK_PC,       pc)
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| STRUCT_FIELD (long, 4, XT_STK_PS,       ps)
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| STRUCT_FIELD (long, 4, XT_STK_A0,       a0)
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| [..]
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| STRUCT_FIELD (long, 4, XT_STK_A15,      a15)
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| STRUCT_FIELD (long, 4, XT_STK_SAR,      sar)
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| STRUCT_FIELD (long, 4, XT_STK_EXCCAUSE, exccause)
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| STRUCT_FIELD (long, 4, XT_STK_EXCVADDR, excvaddr)
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| STRUCT_FIELD (long, 4, XT_STK_LBEG,   lbeg)
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| STRUCT_FIELD (long, 4, XT_STK_LEND,   lend)
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| STRUCT_FIELD (long, 4, XT_STK_LCOUNT, lcount)
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| // Temporary space for saving stuff during window spill 
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| STRUCT_FIELD (long, 4, XT_STK_TMP0,   tmp0)
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| STRUCT_FIELD (long, 4, XT_STK_TMP1,   tmp1)
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| STRUCT_FIELD (long, 4, XT_STK_TMP2,   tmp2)
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| STRUCT_FIELD (long, 4, XT_STK_VPRI,   vpri)
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| STRUCT_FIELD (long, 4, XT_STK_OVLY,   ovly)
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| #endif
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| STRUCT_END(XtExcFrame)
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| */
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| 
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| 
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| static void dumpHwToRegfile(XtExcFrame *frame) {
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| 	int i;
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| 	long *frameAregs=&frame->a0;
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| 	gdbRegFile.pc=frame->pc;
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| 	for (i=0; i<16; i++) gdbRegFile.a[i]=frameAregs[i];
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| 	for (i=16; i<64; i++) gdbRegFile.a[i]=0xDEADBEEF;
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| 	gdbRegFile.lbeg=frame->lbeg;
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| 	gdbRegFile.lend=frame->lend;
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| 	gdbRegFile.lcount=frame->lcount;
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| 	gdbRegFile.sar=frame->sar;
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| 	//All windows have been spilled to the stack by the ISR routines. The following values should indicate that.
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| 	gdbRegFile.sar=frame->sar;
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| 	gdbRegFile.windowbase=0; //0
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| 	gdbRegFile.windowstart=0x1; //1
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| 	gdbRegFile.configid0=0xdeadbeef; //ToDo
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| 	gdbRegFile.configid1=0xdeadbeef; //ToDo
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| 	gdbRegFile.ps=frame->ps-PS_EXCM_MASK;
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| 	gdbRegFile.threadptr=0xdeadbeef; //ToDo
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| 	gdbRegFile.br=0xdeadbeef; //ToDo
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| 	gdbRegFile.scompare1=0xdeadbeef; //ToDo
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| 	gdbRegFile.acclo=0xdeadbeef; //ToDo
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| 	gdbRegFile.acchi=0xdeadbeef; //ToDo
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| 	gdbRegFile.m0=0xdeadbeef; //ToDo
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| 	gdbRegFile.m1=0xdeadbeef; //ToDo
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| 	gdbRegFile.m2=0xdeadbeef; //ToDo
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| 	gdbRegFile.m3=0xdeadbeef; //ToDo
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| 	gdbRegFile.expstate=frame->exccause; //ToDo
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| }
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| 
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| 
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| //Send the reason execution is stopped to GDB.
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| static void sendReason() {
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| 	//exception-to-signal mapping
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| 	char exceptionSignal[]={4,31,11,11,2,6,8,0,6,7,0,0,7,7,7,7};
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| 	int i=0;
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| 	gdbPacketStart();
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| 	gdbPacketChar('T');
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| 	i=gdbRegFile.expstate&0x7f;
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| 	if (i<sizeof(exceptionSignal)) {
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| 		gdbPacketHex(exceptionSignal[i], 8); 
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| 	} else {
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| 		gdbPacketHex(11, 8);
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| 	}
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| 	gdbPacketEnd();
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| }
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| 
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| //Handle a command as received from GDB.
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| static int gdbHandleCommand(unsigned char *cmd, int len) {
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| 	//Handle a command
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| 	int i, j, k;
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| 	unsigned char *data=cmd+1;
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| 	if (cmd[0]=='g') {		//send all registers to gdb
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| 		int *p=(int*)&gdbRegFile;
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| 		gdbPacketStart();
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| 		for (i=0; i<sizeof(GdbRegFile)/4; i++) gdbPacketHex(iswap(*p++), 32);
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| 		gdbPacketEnd();
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| 	} else if (cmd[0]=='G') {	//receive content for all registers from gdb
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| 		int *p=(int*)&gdbRegFile;
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| 		for (i=0; i<sizeof(GdbRegFile)/4; i++) *p++=iswap(gdbGetHexVal(&data, 32));;
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| 		gdbPacketStart();
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| 		gdbPacketStr("OK");
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| 		gdbPacketEnd();
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| 	} else if (cmd[0]=='m') {	//read memory to gdb
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| 		i=gdbGetHexVal(&data, -1);
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| 		data++;
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| 		j=gdbGetHexVal(&data, -1);
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| 		gdbPacketStart();
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| 		for (k=0; k<j; k++) {
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| 			gdbPacketHex(readbyte(i++), 8);
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| 		}
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| 		gdbPacketEnd();
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| 	} else if (cmd[0]=='?') {	//Reply with stop reason
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| 		sendReason();
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| 	} else {
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| 		//We don't recognize or support whatever GDB just sent us.
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| 		gdbPacketStart();
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| 		gdbPacketEnd();
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| 		return ST_ERR;
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| 	}
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| 	return ST_OK;
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| }
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| 
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| 
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| //Lower layer: grab a command packet and check the checksum
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| //Calls gdbHandleCommand on the packet if the checksum is OK
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| //Returns ST_OK on success, ST_ERR when checksum fails, a 
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| //character if it is received instead of the GDB packet
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| //start char.
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| static int gdbReadCommand() {
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| 	unsigned char c;
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| 	unsigned char chsum=0, rchsum;
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| 	unsigned char sentchs[2];
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| 	int p=0;
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| 	unsigned char *ptr;
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| 	c=gdbRecvChar();
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| 	if (c!='$') return c;
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| 	while(1) {
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| 		c=gdbRecvChar();
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| 		if (c=='#') {	//end of packet, checksum follows
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| 			cmd[p]=0;
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| 			break;
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| 		}
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| 		chsum+=c;
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| 		if (c=='$') {
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| 			//Wut, restart packet?
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| 			chsum=0;
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| 			p=0;
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| 			continue;
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| 		}
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| 		if (c=='}') {		//escape the next char
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| 			c=gdbRecvChar();
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| 			chsum+=c;
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| 			c^=0x20;
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| 		}
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| 		cmd[p++]=c;
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| 		if (p>=PBUFLEN) return ST_ERR;
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| 	}
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| 	//A # has been received. Get and check the received chsum.
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| 	sentchs[0]=gdbRecvChar();
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| 	sentchs[1]=gdbRecvChar();
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| 	ptr=&sentchs[0];
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| 	rchsum=gdbGetHexVal(&ptr, 8);
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| 	if (rchsum!=chsum) {
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| 		gdbSendChar('-');
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| 		return ST_ERR;
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| 	} else {
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| 		gdbSendChar('+');
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| 		return gdbHandleCommand(cmd, p);
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| 	}
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| }
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| 
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| 
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| 
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| void esp_gdbstub_panic_handler(XtExcFrame *frame) {
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| 	dumpHwToRegfile(frame);
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| 	//Make sure txd/rxd are enabled
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| 	gpio_pullup_dis(1);
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| 	PIN_FUNC_SELECT(PERIPHS_IO_MUX_U0RXD_U, FUNC_U0RXD_U0RXD);
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| 	PIN_FUNC_SELECT(PERIPHS_IO_MUX_U0TXD_U, FUNC_U0TXD_U0TXD);
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| 
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| 	sendReason();
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| 	while(gdbReadCommand()!=ST_CONT);
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| 	while(1);
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| }
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| 
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