200 lines
5.3 KiB
C
200 lines
5.3 KiB
C
#include "kernel.h"
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#include "common.h"
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extern char __bss[], __bss_end[], __stack_top[];
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extern char __free_ram[], __free_ram_end[];
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paddr_t alloc_pages(uint32_t n)
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{
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static paddr_t next_paddr = (paddr_t)__free_ram;
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paddr_t paddr = next_paddr;
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next_paddr += n * PAGE_SIZE;
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if (next_paddr > (paddr_t)__free_ram_end)
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PANIC("OOM BABY");
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memset((void *)paddr, 0, n * PAGE_SIZE);
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return paddr;
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}
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struct 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__("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),
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"r"(a6), "r"(a7)
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: "memory");
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return (struct sbiret){.error = a0, .value = a1};
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}
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__attribute__((naked))
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__attribute__((aligned(4))) void
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kernel_entry(void)
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{
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__asm__ __volatile__(
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"csrw sscratch, sp\n"
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"addi sp, sp, -4 * 31\n"
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"sw ra, 4 * 0(sp)\n"
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"sw gp, 4 * 1(sp)\n"
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"sw tp, 4 * 2(sp)\n"
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"sw t0, 4 * 3(sp)\n"
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"sw t1, 4 * 4(sp)\n"
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"sw t2, 4 * 5(sp)\n"
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"sw t3, 4 * 6(sp)\n"
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"sw t4, 4 * 7(sp)\n"
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"sw t5, 4 * 8(sp)\n"
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"sw t6, 4 * 9(sp)\n"
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"sw a0, 4 * 10(sp)\n"
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"sw a1, 4 * 11(sp)\n"
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"sw a2, 4 * 12(sp)\n"
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"sw a3, 4 * 13(sp)\n"
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"sw a4, 4 * 14(sp)\n"
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"sw a5, 4 * 15(sp)\n"
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"sw a6, 4 * 16(sp)\n"
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"sw a7, 4 * 17(sp)\n"
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"sw s0, 4 * 18(sp)\n"
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"sw s1, 4 * 19(sp)\n"
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"sw s2, 4 * 20(sp)\n"
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"sw s3, 4 * 21(sp)\n"
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"sw s4, 4 * 22(sp)\n"
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"sw s5, 4 * 23(sp)\n"
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"sw s6, 4 * 24(sp)\n"
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"sw s7, 4 * 25(sp)\n"
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"sw s8, 4 * 26(sp)\n"
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"sw s9, 4 * 27(sp)\n"
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"sw s10, 4 * 28(sp)\n"
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"sw s11, 4 * 29(sp)\n"
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"csrr a0, sscratch\n"
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"sw a0, 4 * 30(sp)\n"
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"mv a0, sp\n"
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"call handle_trap\n"
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"lw ra, 4 * 0(sp)\n"
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"lw gp, 4 * 1(sp)\n"
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"lw tp, 4 * 2(sp)\n"
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"lw t0, 4 * 3(sp)\n"
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"lw t1, 4 * 4(sp)\n"
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"lw t2, 4 * 5(sp)\n"
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"lw t3, 4 * 6(sp)\n"
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"lw t4, 4 * 7(sp)\n"
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"lw t5, 4 * 8(sp)\n"
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"lw t6, 4 * 9(sp)\n"
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"lw a0, 4 * 10(sp)\n"
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"lw a1, 4 * 11(sp)\n"
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"lw a2, 4 * 12(sp)\n"
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"lw a3, 4 * 13(sp)\n"
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"lw a4, 4 * 14(sp)\n"
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"lw a5, 4 * 15(sp)\n"
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"lw a6, 4 * 16(sp)\n"
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"lw a7, 4 * 17(sp)\n"
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"lw s0, 4 * 18(sp)\n"
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"lw s1, 4 * 19(sp)\n"
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"lw s2, 4 * 20(sp)\n"
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"lw s3, 4 * 21(sp)\n"
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"lw s4, 4 * 22(sp)\n"
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"lw s5, 4 * 23(sp)\n"
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"lw s6, 4 * 24(sp)\n"
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"lw s7, 4 * 25(sp)\n"
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"lw s8, 4 * 26(sp)\n"
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"lw s9, 4 * 27(sp)\n"
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"lw s10, 4 * 28(sp)\n"
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"lw s11, 4 * 29(sp)\n"
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"lw sp, 4 * 30(sp)\n"
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"sret\n");
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}
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__attribute__((naked)) void switch_context(uint32_t *prev_sp,
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uint32_t *next_sp)
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{
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__asm__ __volatile__(
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"addi sp, sp, -13 * 4\n" // Allocate stack space for 13 4 byte registers
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"sw ra, 0 * 4(sp)\n" // Save callee-saved registers only
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"sw s0, 1 * 4(sp)\n"
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"sw s1, 2 * 4(sp)\n"
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"sw s2, 3 * 4(sp)\n"
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"sw s3, 4 * 4(sp)\n"
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"sw s4, 5 * 4(sp)\n"
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"sw s5, 6 * 4(sp)\n"
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"sw s6, 7 * 4(sp)\n"
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"sw s7, 8 * 4(sp)\n"
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"sw s8, 9 * 4(sp)\n"
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"sw s9, 10 * 4(sp)\n"
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"sw s10, 11 * 4(sp)\n"
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"sw s11, 12 * 4(sp)\n"
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"sw sp, (a0)\n" // *prev_sp = sp;
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"lw sp, (a1)\n" // Switch stack pointer (sp) here
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"lw ra, 0 * 4(sp)\n" // Restore callee-saved-registers only
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"lw s0, 1 * 4(sp)\n"
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"lw s1, 2 * 4(sp)\n"
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"lw s2, 3 * 4(sp)\n"
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"lw s3, 4 * 4(sp)\n"
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"lw s4, 5 * 4(sp)\n"
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"lw s5, 6 * 4(sp)\n"
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"lw s6, 7 * 4(sp)\n"
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"lw s7, 8 * 4(sp)\n"
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"lw s8, 9 * 4(sp)\n"
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"lw s9, 10 * 4(sp)\n"
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"lw s10, 11 * 4(sp)\n"
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"lw s11, 12 * 4(sp)\n"
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"addi sp, sp * 4\n"
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"ret\n"
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);
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}
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void handle_trap(struct trap_frame *f)
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{
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uint32_t scause = READ_CSR(scause);
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uint32_t stval = READ_CSR(stval);
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uint32_t user_pc = READ_CSR(sepc);
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PANIC("unexpected trap scause=%x, stval=%x, user_pc=%x\n", scause, stval, user_pc);
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}
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void putchar(char ch)
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{
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sbi_call(ch, 0, 0, 0, 0, 0, 0, 1 /* Console Putchar */);
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}
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void kernel_main(void)
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{
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memset(__bss, 0, (size_t)__bss_end - (size_t)__bss);
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WRITE_CSR(stvec, (uint32_t)kernel_entry);
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paddr_t paddr0 = alloc_pages(2);
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paddr_t paddr1 = alloc_pages(1);
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printf("alloc_pages test: paddr0=%x\n", paddr0);
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printf("alloc_pages test: paddr1=%x\n", paddr1);
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PANIC("Booted");
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for (;;)
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{
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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)) void
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boot(void)
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{
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__asm__ __volatile__(
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"mv sp, %[stack_top]\n" // Set the stack pointer
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"j kernel_main\n" // Jump to the kernel main function
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:
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: [stack_top] "r"(__stack_top) // Pass the stack top address as %[stack_top]
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);
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}
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