《操作系统》的实验代码。
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#ifndef __LIBS_X86_H__
#define __LIBS_X86_H__
#include <defs.h>
#define do_div(n, base) ({ \
unsigned long __upper, __low, __high, __mod, __base; \
__base = (base); \
asm("" : "=a" (__low), "=d" (__high) : "A" (n)); \
__upper = __high; \
if (__high != 0) { \
__upper = __high % __base; \
__high = __high / __base; \
} \
asm("divl %2" : "=a" (__low), "=d" (__mod) \
: "rm" (__base), "0" (__low), "1" (__upper)); \
asm("" : "=A" (n) : "a" (__low), "d" (__high)); \
__mod; \
})
static inline uint8_t inb(uint16_t port) __attribute__((always_inline));
static inline void insl(uint32_t port, void *addr, int cnt) __attribute__((always_inline));
static inline void outb(uint16_t port, uint8_t data) __attribute__((always_inline));
static inline void outw(uint16_t port, uint16_t data) __attribute__((always_inline));
static inline uint32_t read_ebp(void) __attribute__((always_inline));
/* Pseudo-descriptors used for LGDT, LLDT(not used) and LIDT instructions. */
struct pseudodesc {
uint16_t pd_lim; // Limit
uint32_t pd_base; // Base address
} __attribute__ ((packed));
static inline void lidt(struct pseudodesc *pd) __attribute__((always_inline));
static inline void sti(void) __attribute__((always_inline));
static inline void cli(void) __attribute__((always_inline));
static inline void ltr(uint16_t sel) __attribute__((always_inline));
static inline uint8_t
inb(uint16_t port) {
uint8_t data;
asm volatile ("inb %1, %0" : "=a" (data) : "d" (port));
return data;
}
static inline void
insl(uint32_t port, void *addr, int cnt) {
asm volatile (
"cld;"
"repne; insl;"
: "=D" (addr), "=c" (cnt)
: "d" (port), "0" (addr), "1" (cnt)
: "memory", "cc");
}
static inline void
outb(uint16_t port, uint8_t data) {
asm volatile ("outb %0, %1" :: "a" (data), "d" (port));
}
static inline void
outw(uint16_t port, uint16_t data) {
asm volatile ("outw %0, %1" :: "a" (data), "d" (port));
}
static inline uint32_t
read_ebp(void) {
uint32_t ebp;
asm volatile ("movl %%ebp, %0" : "=r" (ebp));
return ebp;
}
static inline void
lidt(struct pseudodesc *pd) {
asm volatile ("lidt (%0)" :: "r" (pd));
}
static inline void
sti(void) {
asm volatile ("sti");
}
static inline void
cli(void) {
asm volatile ("cli");
}
static inline void
ltr(uint16_t sel) {
asm volatile ("ltr %0" :: "r" (sel));
}
static inline int __strcmp(const char *s1, const char *s2) __attribute__((always_inline));
static inline char *__strcpy(char *dst, const char *src) __attribute__((always_inline));
static inline void *__memset(void *s, char c, size_t n) __attribute__((always_inline));
static inline void *__memmove(void *dst, const void *src, size_t n) __attribute__((always_inline));
static inline void *__memcpy(void *dst, const void *src, size_t n) __attribute__((always_inline));
#ifndef __HAVE_ARCH_STRCMP
#define __HAVE_ARCH_STRCMP
static inline int
__strcmp(const char *s1, const char *s2) {
int d0, d1, ret;
asm volatile (
"1: lodsb;"
"scasb;"
"jne 2f;"
"testb %%al, %%al;"
"jne 1b;"
"xorl %%eax, %%eax;"
"jmp 3f;"
"2: sbbl %%eax, %%eax;"
"orb $1, %%al;"
"3:"
: "=a" (ret), "=&S" (d0), "=&D" (d1)
: "1" (s1), "2" (s2)
: "memory");
return ret;
}
#endif /* __HAVE_ARCH_STRCMP */
#ifndef __HAVE_ARCH_STRCPY
#define __HAVE_ARCH_STRCPY
static inline char *
__strcpy(char *dst, const char *src) {
int d0, d1, d2;
asm volatile (
"1: lodsb;"
"stosb;"
"testb %%al, %%al;"
"jne 1b;"
: "=&S" (d0), "=&D" (d1), "=&a" (d2)
: "0" (src), "1" (dst) : "memory");
return dst;
}
#endif /* __HAVE_ARCH_STRCPY */
#ifndef __HAVE_ARCH_MEMSET
#define __HAVE_ARCH_MEMSET
static inline void *
__memset(void *s, char c, size_t n) {
int d0, d1;
asm volatile (
"rep; stosb;"
: "=&c" (d0), "=&D" (d1)
: "0" (n), "a" (c), "1" (s)
: "memory");
return s;
}
#endif /* __HAVE_ARCH_MEMSET */
#ifndef __HAVE_ARCH_MEMMOVE
#define __HAVE_ARCH_MEMMOVE
static inline void *
__memmove(void *dst, const void *src, size_t n) {
if (dst < src) {
return __memcpy(dst, src, n);
}
int d0, d1, d2;
asm volatile (
"std;"
"rep; movsb;"
"cld;"
: "=&c" (d0), "=&S" (d1), "=&D" (d2)
: "0" (n), "1" (n - 1 + src), "2" (n - 1 + dst)
: "memory");
return dst;
}
#endif /* __HAVE_ARCH_MEMMOVE */
#ifndef __HAVE_ARCH_MEMCPY
#define __HAVE_ARCH_MEMCPY
static inline void *
__memcpy(void *dst, const void *src, size_t n) {
int d0, d1, d2;
asm volatile (
"rep; movsl;"
"movl %4, %%ecx;"
"andl $3, %%ecx;"
"jz 1f;"
"rep; movsb;"
"1:"
: "=&c" (d0), "=&D" (d1), "=&S" (d2)
: "0" (n / 4), "g" (n), "1" (dst), "2" (src)
: "memory");
return dst;
}
#endif /* __HAVE_ARCH_MEMCPY */
#endif /* !__LIBS_X86_H__ */