MNRS-BM-BSP/libwrap/semihosting/semihosting.c

90 lines
2.9 KiB
C

#include <stdint.h>
#include <stdarg.h>
#include <stddef.h>
#include "semihosting.h"
#define SEMIHOSTING_SYS_OPEN 0x01
#define SEMIHOSTING_SYS_CLOSE 0x02
#define SEMIHOSTING_SYS_WRITEC 0x03
#define SEMIHOSTING_SYS_WRITE0 0x04
#define SEMIHOSTING_SYS_WRITE 0x05
#define SEMIHOSTING_SYS_READ 0x06
#define SEMIHOSTING_SYS_READC 0x07
#define SEMIHOSTING_SYS_ISERROR 0x08
#define SEMIHOSTING_SYS_ISTTY 0x09
#define SEMIHOSTING_SYS_SEEK 0x0A
#define SEMIHOSTING_SYS_FLEN 0x0C
#define SEMIHOSTING_SYS_TMPNAM 0x0D
#define SEMIHOSTING_SYS_REMOVE 0x0E
#define SEMIHOSTING_SYS_RENAME 0x0F
#define SEMIHOSTING_SYS_CLOCK 0x10
#define SEMIHOSTING_SYS_TIME 0x11
#define SEMIHOSTING_SYS_SYSTEM 0x12
#define SEMIHOSTING_SYS_ERRNO 0x13
#define SEMIHOSTING_SYS_GET_CMDLINE 0x15
#define SEMIHOSTING_SYS_HEAPINFO 0x16
#define SEMIHOSTING_EnterSVC 0x17
#define SEMIHOSTING_ReportException 0x18
#define SEMIHOSTING_SYS_ELAPSED 0x30
#define SEMIHOSTING_SYS_TICKFREQ 0x31
#define RISCV_SEMIHOSTING_CALL_NUMBER 7
static inline int __attribute__ ((always_inline)) call_host(int reason, void* arg) {
#if 1
// This must always be set back to 0 to cover the case where a host wasn't
// initially present, but only connected while the program was already up and
// running. In that case, trap() suddenly won't be called anymore, so we have to
// clear this variable *before* EBREAK is called.
sh_missing_host = 0;
register int value asm ("a0") = reason;
register void* ptr asm ("a1") = arg;
asm volatile (
// Workaround for RISC-V lack of multiple EBREAKs.
" .option push \n"
" .option norvc \n"
// Force 16-byte alignment to make sure that the 3 instruction fall
// within the same virtual page. If you the instruction straddle a page boundary
// the debugger fetching the instructions could lead to a page fault.
// Note: align 4 means, align by 2 to the power of 4!
" .align 4 \n"
" slli x0, x0, 0x1f \n"
" ebreak \n"
" srai x0, x0, 0x07 \n"
" .option pop \n"
: "=r" (value) /* Outputs */
: "0" (value), "r" (ptr), [swi] "i" (RISCV_SEMIHOSTING_CALL_NUMBER) /* Inputs */
: "memory" /* Clobbers */
);
return value;
#else
return 0;
#endif
}
void sh_write0(const char* buf)
{
// Print zero-terminated string
call_host(SEMIHOSTING_SYS_WRITE0, (void*) buf);
}
void sh_writec(char c)
{
// Print single character
call_host(SEMIHOSTING_SYS_WRITEC, (void*)&c);
}
char sh_readc(void)
{
// Read character from keyboard. (Blocking operation!)
char c = call_host(SEMIHOSTING_SYS_READC, (void*)NULL);
if (sh_missing_host)
return 0;
else
return c;
}