57 lines
1.5 KiB
C
57 lines
1.5 KiB
C
#include "kernel.h"
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extern uint8_t __bss[], __bss_end[], __stack_top[];
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sbiret sbi_call(long arg0, long arg1, long arg2, long arg3, long arg4,
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long arg5, long fid, long eid)
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{
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register long a0 __asm__("a0") = arg0;
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register long a1 __asm__("a1") = arg1;
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register long a2 __asm__("a2") = arg2;
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register long a3 __asm__("a3") = arg3;
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register long a4 __asm__("a4") = arg4;
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register long a5 __asm__("a5") = arg5;
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register long a6 __asm__("a6") = fid;
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register long a7 __asm__("a7") = eid;
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__asm__ __volatile__(
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"ecall"
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: "=r"(a0), "=r"(a1)
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: "r"(a0), "r"(a1), "r"(a2), "r"(a3), "r"(a4), "r"(a5), "r"(a6), "r"(a7)
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: "memory"
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);
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return (sbiret) { .error = a0, .value = a1 };
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}
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void putchar(char c)
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{
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// 1 => sbi_console_putchar()
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sbi_call(c, 0, 0, 0, 0, 0, 0, 1);
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}
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void kernel_main(void)
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{
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const char *s = "\n\nHello World!\n";
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for (int i = 0; s[i] != '\0'; i++) {
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putchar(s[i]);
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}
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while(1) {
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// wfi -> wait for interrupt
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__asm__ __volatile__("wfi");
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}
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}
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__attribute__((section(".text.boot")))
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__attribute__((naked))
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void boot(void)
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{
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__asm__ __volatile__ (
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"mv sp, %[stack_top]\n" // Initialize the kernel stack pointer
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"j kernel_main\n" // Unconditional jump to kernel_main
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: // No output
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: [stack_top] "r" (__stack_top) // Pass the stack top address
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);
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}
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