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52 lines
1.3 KiB
52 lines
1.3 KiB
2 years ago
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/*
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* The supporting library for applications.
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* Actually, supporting routines for applications are catalogued as the user
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* library. we don't do that in PKE to make the relationship between application
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* and user library more straightforward.
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*/
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#include "user_lib.h"
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#include "util/types.h"
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#include "util/snprintf.h"
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#include "kernel/syscall.h"
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int do_user_call(uint64 sysnum, uint64 a1, uint64 a2, uint64 a3, uint64 a4, uint64 a5, uint64 a6,
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uint64 a7) {
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int ret;
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// before invoking the syscall, arguments of do_user_call are already loaded into the argument
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// registers (a0-a7) of our (emulated) risc-v machine.
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asm volatile(
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"ecall\n"
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"sw a0, %0" // returns a 32-bit value
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: "=m"(ret)
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:
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: "memory");
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return ret;
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}
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//
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// printu() supports user/lab1_1_helloworld.c
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//
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int printu(const char* s, ...) {
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va_list vl;
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va_start(vl, s);
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char out[256]; // fixed buffer size.
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int res = vsnprintf(out, sizeof(out), s, vl);
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va_end(vl);
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const char* buf = out;
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size_t n = res < sizeof(out) ? res : sizeof(out);
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// make a syscall to implement the required functionality.
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return do_user_call(SYS_user_print, (uint64)buf, n, 0, 0, 0, 0, 0);
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}
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//
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// applications need to call exit to quit execution.
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//
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int exit(int code) {
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return do_user_call(SYS_user_exit, code, 0, 0, 0, 0, 0, 0);
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}
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