first semihosting integration
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@ -41,7 +41,7 @@ trap_entry:
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csrr a0, mcause
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csrr a1, mepc
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mv a2, sp
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call handle_trap
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call trap
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csrw mepc, a0
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#ifndef __riscv_abi_rve
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addi sp, sp, -8*REGBYTES
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@ -0,0 +1,54 @@
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IF(NOT DEFINED _MK_LIBWRAP)
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SET(_MK_LIBWRAP TRUE)
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SET(LIBWRAP_DIR ${CMAKE_CURRENT_LIST_DIR})
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SET(LIBWRAP_SRCS
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${LIBWRAP_DIR}/stdlib/malloc.c
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${LIBWRAP_DIR}/sys/open.c
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${LIBWRAP_DIR}/sys/lseek.c
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${LIBWRAP_DIR}/sys/read.c
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${LIBWRAP_DIR}/sys/write.c
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${LIBWRAP_DIR}/sys/fstat.c
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${LIBWRAP_DIR}/sys/stat.c
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${LIBWRAP_DIR}/sys/close.c
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${LIBWRAP_DIR}/sys/link.c
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${LIBWRAP_DIR}/sys/unlink.c
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${LIBWRAP_DIR}/sys/execve.c
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${LIBWRAP_DIR}/sys/fork.c
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${LIBWRAP_DIR}/sys/getpid.c
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${LIBWRAP_DIR}/sys/kill.c
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${LIBWRAP_DIR}/sys/wait.c
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${LIBWRAP_DIR}/sys/isatty.c
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${LIBWRAP_DIR}/sys/times.c
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${LIBWRAP_DIR}/sys/sbrk.c
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${LIBWRAP_DIR}/sys/_exit.c
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${LIBWRAP_DIR}/misc/write_hex.c
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${LIBWRAP_DIR}/sys/printf.c
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)
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IF(${SEMIHOSTING})
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SET(LIBWRAP_SRCS ${LIBWRAP_SRCS} ${LIBWRAP_DIR}/semihosting/semihosting.c ${LIBWRAP_DIR}/semihosting/trap.c)
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ENDIF()
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SET(LIBWRAP_SYMS malloc free open lseek read write fstat stat close link unlink execve fork getpid jukk wait isatty times sbrk _exit printf puts)
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# Includes
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INCLUDE_DIRECTORIES(
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${LIBWRAP_DIR}
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${LIBWRAP_DIR}/../include
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${LIBWRAP_DIR}/../drivers
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${LIBWRAP_DIR}/../env
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${LIBWRAP_DIR}/../env/iss
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)
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ADD_LIBRARY(LIBWRAP_TGC STATIC ${LIBWRAP_SRCS})
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TARGET_COMPILE_OPTIONS(LIBWRAP_TGC PRIVATE -march=${RISCV_ARCH}_zicsr_zifencei -mabi=${RISCV_ABI} "-DBOARD_${BOARD}")
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FOREACH(SYM ${LIBWRAP_SYMS})
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LIST(APPEND WRAP_LDFLAGS "-Wl,--wrap=${SYM}")
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ENDFOREACH()
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SET(LIBWRAP_TGC_LDFLAGS ${WRAP_LDFLAGS} "-Wl,--start-group" "-Wl,--end-group")
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ENDIF(NOT DEFINED _MK_LIBWRAP)
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@ -0,0 +1,90 @@
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#include <stdint.h>
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#include <stdarg.h>
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#include <stddef.h>
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#include "semihosting.h"
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#define SEMIHOSTING_SYS_OPEN 0x01
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#define SEMIHOSTING_SYS_CLOSE 0x02
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#define SEMIHOSTING_SYS_WRITEC 0x03
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#define SEMIHOSTING_SYS_WRITE0 0x04
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#define SEMIHOSTING_SYS_WRITE 0x05
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#define SEMIHOSTING_SYS_READ 0x06
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#define SEMIHOSTING_SYS_READC 0x07
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#define SEMIHOSTING_SYS_ISERROR 0x08
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#define SEMIHOSTING_SYS_ISTTY 0x09
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#define SEMIHOSTING_SYS_SEEK 0x0A
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#define SEMIHOSTING_SYS_FLEN 0x0C
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#define SEMIHOSTING_SYS_TMPNAM 0x0D
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#define SEMIHOSTING_SYS_REMOVE 0x0E
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#define SEMIHOSTING_SYS_RENAME 0x0F
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#define SEMIHOSTING_SYS_CLOCK 0x10
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#define SEMIHOSTING_SYS_TIME 0x11
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#define SEMIHOSTING_SYS_SYSTEM 0x12
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#define SEMIHOSTING_SYS_ERRNO 0x13
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#define SEMIHOSTING_SYS_GET_CMDLINE 0x15
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#define SEMIHOSTING_SYS_HEAPINFO 0x16
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#define SEMIHOSTING_EnterSVC 0x17
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#define SEMIHOSTING_ReportException 0x18
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#define SEMIHOSTING_SYS_ELAPSED 0x30
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#define SEMIHOSTING_SYS_TICKFREQ 0x31
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#define RISCV_SEMIHOSTING_CALL_NUMBER 7
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static inline int __attribute__ ((always_inline)) call_host(int reason, void* arg) {
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#if 1
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// This must always be set back to 0 to cover the case where a host wasn't
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// initially present, but only connected while the program was already up and
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// running. In that case, trap() suddenly won't be called anymore, so we have to
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// clear this variable *before* EBREAK is called.
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sh_missing_host = 0;
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register int value asm ("a0") = reason;
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register void* ptr asm ("a1") = arg;
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asm volatile (
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// Workaround for RISC-V lack of multiple EBREAKs.
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" .option push \n"
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" .option norvc \n"
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// Force 16-byte alignment to make sure that the 3 instruction fall
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// within the same virtual page. If you the instruction straddle a page boundary
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// the debugger fetching the instructions could lead to a page fault.
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// Note: align 4 means, align by 2 to the power of 4!
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" .align 4 \n"
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" slli x0, x0, 0x1f \n"
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" ebreak \n"
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" srai x0, x0, 0x07 \n"
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" .option pop \n"
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: "=r" (value) /* Outputs */
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: "0" (value), "r" (ptr), [swi] "i" (RISCV_SEMIHOSTING_CALL_NUMBER) /* Inputs */
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: "memory" /* Clobbers */
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);
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return value;
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#else
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return 0;
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#endif
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}
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void sh_write0(const char* buf)
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{
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// Print zero-terminated string
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call_host(SEMIHOSTING_SYS_WRITE0, (void*) buf);
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}
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void sh_writec(char c)
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{
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// Print single character
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call_host(SEMIHOSTING_SYS_WRITEC, (void*)&c);
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}
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char sh_readc(void)
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{
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// Read character from keyboard. (Blocking operation!)
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char c = call_host(SEMIHOSTING_SYS_READC, (void*)NULL);
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if (sh_missing_host)
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return 0;
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else
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return c;
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}
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@ -0,0 +1,14 @@
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#ifndef SEMIHOSTING_H
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#define SEMIHOSTING_H
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//int32_t trace_write(const char* buf, uint32_t nbyte);
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void sh_write0(const char* buf);
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void sh_writec(char c);
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char sh_readc(void);
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int getchar(void);
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extern int sh_missing_host;
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#endif
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@ -0,0 +1,60 @@
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#include <stdint.h>
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#include <stdlib.h>
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#include <math.h>
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#include "encoding.h"
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#define EBREAK_OPCODE 0x00100073
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#define EBREAK_MCAUSE 0x00000003
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#define SLLI_X0_X0_0X1F_OPCODE 0x01f01013
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#define SRAI_X0_X0_0X07_OPCODE 0x40705013
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int sh_missing_host = 0;
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void trap()
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{
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uint32_t mepc = read_csr(0x341); // Address of trap
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uint32_t mtval = read_csr(0x343); // Instruction value of trap
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uint32_t mcause = read_csr(0x342); // Reason for the trap
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if (mcause == EBREAK_MCAUSE && mtval == EBREAK_OPCODE){
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// This trap was caused by an EBREAK...
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int aligned = ((mepc-4) & 0x0f) == 0;
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if (aligned
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&& *(uint32_t *)mepc == EBREAK_OPCODE
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&& *(uint32_t *)(mepc-4) == SLLI_X0_X0_0X1F_OPCODE
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&& *(uint32_t *)(mepc+4) == SRAI_X0_X0_0X07_OPCODE)
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{
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// The EBREAK was part of the semihosting call. (See semihosting.c)
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//
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// If a debugger were connected, this would have resulted in a CPU halt,
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// and the debugger would have serviced the the semihosting call.
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//
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// However, the semihosting function was called without a debugger being
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// attached. The best course of action is to simply return from the trap
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// and let the semihosting function continue after the call to EBREAK to
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// prevent the CPU from hanging in the trap handler.
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write_csr(mepc, mepc+4);
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// Set a global variable to tell the semihosting code the the semihosting
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// call
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// didn't execute on the host.
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sh_missing_host = 1;
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return;
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}
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// EBREAK was not part of a semihosting call. This should not have happened.
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// Hang forever.
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while(1)
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;
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}
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// Trap was issued for another reason than an EBREAK.
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// Replace the code below with whatever trap handler you'd normally use. (e.g. interrupt
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// processing.)
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while(1)
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;
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}
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