127 lines
2.6 KiB
C
127 lines
2.6 KiB
C
#include <user/syscall.h>
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// 第一个冒号区间：汇编命令
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// 第二个冒号区间：输出操作符扩展
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// "=a" 这条命令结束后将eax寄存器的值赋给ret变量
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// 第三个冒号区间：输入操作符扩展
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// "a" 将变量赋给eax寄存器
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// "b" 将变量赋给ebx寄存器
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// "c" 将变量赋给ecx寄存器
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// "d" 将变量赋给edx寄存器
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// "S" 将变量赋给esi寄存器
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// "D" 将变量赋给edi寄存器
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// 第四个冒号区间：指令约束，当汇编指令会修改相关操作时需要修改
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// 最主要是防被gcc编译器优化
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// "a/b/c/d/S/D" 提醒编译器这些寄存器的值会在汇编指令执行中被修改
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// "cc" 提醒编译器eflags寄存器的值在汇编指令执行中会被修改
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// "memory" 提醒编译器内存中的数据在汇编指令执行中会被修改
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ssize_t
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syscall0(size_t NR_syscall)
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{
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ssize_t ret;
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asm volatile("int $0x80"
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: "=a"(ret)
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: "a" (NR_syscall)
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: "cc", "memory");
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return ret;
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}
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ssize_t
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syscall1(size_t NR_syscall, size_t p1)
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{
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ssize_t ret;
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asm volatile("int $0x80"
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: "=a"(ret)
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: "a" (NR_syscall),
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"b" (p1)
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: "cc", "memory");
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return ret;
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}
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ssize_t syscall2(size_t NR_syscall, size_t p1, size_t p2)
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{
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ssize_t ret;
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asm volatile("int $0x80"
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: "=a"(ret)
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: "a" (NR_syscall),
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"b" (p1),
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"c" (p2)
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: "cc", "memory");
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return ret;
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}
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ssize_t syscall3(size_t NR_syscall, size_t p1, size_t p2, size_t p3)
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{
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ssize_t ret;
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asm volatile("int $0x80"
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: "=a"(ret)
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: "a" (NR_syscall),
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"b" (p1),
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"c" (p2),
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"d" (p3)
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: "cc", "memory");
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return ret;
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}
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ssize_t syscall4(size_t NR_syscall, size_t p1, size_t p2,
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size_t p3, size_t p4)
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{
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ssize_t ret;
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asm volatile("int $0x80"
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: "=a"(ret)
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: "a" (NR_syscall),
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"b" (p1),
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"c" (p2),
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"d" (p3),
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"S" (p4)
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: "cc", "memory");
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return ret;
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}
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ssize_t syscall5(size_t NR_syscall, size_t p1, size_t p2,
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size_t p3, size_t p4, size_t p5)
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{
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ssize_t ret;
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asm volatile("int $0x80"
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: "=a"(ret)
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: "a" (NR_syscall),
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"b" (p1),
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"c" (p2),
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"d" (p3),
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"S" (p4),
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"D" (p5)
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: "cc", "memory");
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return ret;
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}
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ssize_t
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get_ticks()
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{
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return syscall0(_NR_get_ticks);
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}
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ssize_t
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get_pid()
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{
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return syscall0(_NR_get_pid);
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}
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ssize_t
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read(int fd, void *buf, size_t count)
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{
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return syscall3(_NR_read, fd, (size_t)buf, count);
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}
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ssize_t
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write(int fd, const void *buf, size_t count)
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{
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return syscall3(_NR_write, fd, (size_t)buf, count);
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}
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ssize_t
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delay_ticks(u32 ticks)
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{
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return syscall1(_NR_delay_ticks, ticks);
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}
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ssize_t lml_mmap(int pid, void* src, void* dst, size_t length)
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{
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return syscall4(_NR_mmap, pid, (size_t)src, (size_t)dst, length);
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} |