90 lines
2.9 KiB
C
90 lines
2.9 KiB
C
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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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