bcopy.s

一个嵌入式操作系统(microwindows)的源代码

fastmove_tail:
	movl	_curpcb,%eax
	movl	$fastmove_tail_fault,PCB_ONFAULT(%eax)

	movb	%cl,%al
	shrl	$2,%ecx				/* copy longword-wise */
	cld
	rep
	movsl
	movb	%al,%cl
	andb	$3,%cl				/* copy remaining bytes */
	rep
	movsb

	movl	%ebp,%esp
	popl	%ebp
	ret

	ALIGN_TEXT
fastmove_fault:
	movl	_curpcb,%edi
	addl	$PCB_SAVEFPU,%edi
	movl	%esp,%esi
	cld
	movl	$PCB_SAVEFPU_SIZE>>2,%ecx
	rep
	movsl

	smsw	%ax
	orb	$CR0_TS,%al
	lmsw	%ax
	movl	$0,_npxproc

fastmove_tail_fault:
	movl	%ebp,%esp
	popl	%ebp
	addl	$8,%esp
	popl	%ebx
	popl	%edi
	popl	%esi
	movl	_curpcb,%edx
	movl	$0,PCB_ONFAULT(%edx)
	movl	$EFAULT,%eax
	ret
#endif /* I586_CPU && NNPX > 0 */

/*
 * fu{byte,sword,word} : fetch a byte (sword, word) from user memory
 */
ENTRY(fuword)
	movl	_curpcb,%ecx
	movl	$fusufault,PCB_ONFAULT(%ecx)
	movl	4(%esp),%edx			/* from */

	cmpl	$VM_MAXUSER_ADDRESS-4,%edx	/* verify address is valid */
	ja	fusufault

	movl	(%edx),%eax
	movl	$0,PCB_ONFAULT(%ecx)
	ret

/*
 * These two routines are called from the profiling code, potentially
 * at interrupt time. If they fail, that's okay, good things will
 * happen later. Fail all the time for now - until the trap code is
 * able to deal with this.
 */
ALTENTRY(suswintr)
ENTRY(fuswintr)
	movl	$-1,%eax
	ret

ENTRY(fusword)
	movl	_curpcb,%ecx
	movl	$fusufault,PCB_ONFAULT(%ecx)
	movl	4(%esp),%edx

	cmpl	$VM_MAXUSER_ADDRESS-2,%edx
	ja	fusufault

	movzwl	(%edx),%eax
	movl	$0,PCB_ONFAULT(%ecx)
	ret

ENTRY(fubyte)
	movl	_curpcb,%ecx
	movl	$fusufault,PCB_ONFAULT(%ecx)
	movl	4(%esp),%edx

	cmpl	$VM_MAXUSER_ADDRESS-1,%edx
	ja	fusufault

	movzbl	(%edx),%eax
	movl	$0,PCB_ONFAULT(%ecx)
	ret

	ALIGN_TEXT
fusufault:
	movl	_curpcb,%ecx
	xorl	%eax,%eax
	movl	%eax,PCB_ONFAULT(%ecx)
	decl	%eax
	ret

/*
 * su{byte,sword,word}: write a byte (word, longword) to user memory
 */
ENTRY(suword)
	movl	_curpcb,%ecx
	movl	$fusufault,PCB_ONFAULT(%ecx)
	movl	4(%esp),%edx

#if defined(I386_CPU)

#if defined(I486_CPU) || defined(I586_CPU) || defined(I686_CPU)
	cmpl	$CPUCLASS_386,_cpu_class
	jne	2f				/* we only have to set the right segment selector */
#endif /* I486_CPU || I586_CPU || I686_CPU */

	/* XXX - page boundary crossing is still not handled */
	movl	%edx,%eax
	shrl	$IDXSHIFT,%edx
	andb	$0xfc,%dl

	leal	_PTmap(%edx),%ecx
	shrl	$IDXSHIFT,%ecx
	andb	$0xfc,%cl
	testb	$PG_V,_PTmap(%ecx)		/* PTE page must be valid */
	je	4f
	movb	_PTmap(%edx),%dl
	andb	$PG_V|PG_RW|PG_U,%dl		/* page must be valid and user writable */
	cmpb	$PG_V|PG_RW|PG_U,%dl
	je	1f

4:
	/* simulate a trap */
	pushl	%eax
	call	_trapwrite
	popl	%edx				/* remove junk parameter from stack */
	testl	%eax,%eax
	jnz	fusufault
1:
	movl	4(%esp),%edx
#endif

2:
	cmpl	$VM_MAXUSER_ADDRESS-4,%edx	/* verify address validity */
	ja	fusufault

	movl	8(%esp),%eax
	movl	%eax,(%edx)
	xorl	%eax,%eax
	movl	_curpcb,%ecx
	movl	%eax,PCB_ONFAULT(%ecx)
	ret

ENTRY(susword)
	movl	_curpcb,%ecx
	movl	$fusufault,PCB_ONFAULT(%ecx)
	movl	4(%esp),%edx

#if defined(I386_CPU)

#if defined(I486_CPU) || defined(I586_CPU) || defined(I686_CPU)
	cmpl	$CPUCLASS_386,_cpu_class
	jne	2f
#endif /* I486_CPU || I586_CPU || I686_CPU */

	/* XXX - page boundary crossing is still not handled */
	movl	%edx,%eax
	shrl	$IDXSHIFT,%edx
	andb	$0xfc,%dl

	leal	_PTmap(%edx),%ecx
	shrl	$IDXSHIFT,%ecx
	andb	$0xfc,%cl
	testb	$PG_V,_PTmap(%ecx)		/* PTE page must be valid */
	je	4f
	movb	_PTmap(%edx),%dl
	andb	$PG_V|PG_RW|PG_U,%dl		/* page must be valid and user writable */
	cmpb	$PG_V|PG_RW|PG_U,%dl
	je	1f

4:
	/* simulate a trap */
	pushl	%eax
	call	_trapwrite
	popl	%edx				/* remove junk parameter from stack */
	testl	%eax,%eax
	jnz	fusufault
1:
	movl	4(%esp),%edx
#endif

2:
	cmpl	$VM_MAXUSER_ADDRESS-2,%edx	/* verify address validity */
	ja	fusufault

	movw	8(%esp),%ax
	movw	%ax,(%edx)
	xorl	%eax,%eax
	movl	_curpcb,%ecx			/* restore trashed register */
	movl	%eax,PCB_ONFAULT(%ecx)
	ret

ALTENTRY(suibyte)
ENTRY(subyte)
	movl	_curpcb,%ecx
	movl	$fusufault,PCB_ONFAULT(%ecx)
	movl	4(%esp),%edx

#if defined(I386_CPU)

#if defined(I486_CPU) || defined(I586_CPU) || defined(I686_CPU)
	cmpl	$CPUCLASS_386,_cpu_class
	jne	2f
#endif /* I486_CPU || I586_CPU || I686_CPU */

	movl	%edx,%eax
	shrl	$IDXSHIFT,%edx
	andb	$0xfc,%dl

	leal	_PTmap(%edx),%ecx
	shrl	$IDXSHIFT,%ecx
	andb	$0xfc,%cl
	testb	$PG_V,_PTmap(%ecx)		/* PTE page must be valid */
	je	4f
	movb	_PTmap(%edx),%dl
	andb	$PG_V|PG_RW|PG_U,%dl		/* page must be valid and user writable */
	cmpb	$PG_V|PG_RW|PG_U,%dl
	je	1f

4:
	/* simulate a trap */
	pushl	%eax
	call	_trapwrite
	popl	%edx				/* remove junk parameter from stack */
	testl	%eax,%eax
	jnz	fusufault
1:
	movl	4(%esp),%edx
#endif

2:
	cmpl	$VM_MAXUSER_ADDRESS-1,%edx	/* verify address validity */
	ja	fusufault

	movb	8(%esp),%al
	movb	%al,(%edx)
	xorl	%eax,%eax
	movl	_curpcb,%ecx			/* restore trashed register */
	movl	%eax,PCB_ONFAULT(%ecx)
	ret

/*
 * copyinstr(from, to, maxlen, int *lencopied)
 *	copy a string from from to to, stop when a 0 character is reached.
 *	return ENAMETOOLONG if string is longer than maxlen, and
 *	EFAULT on protection violations. If lencopied is non-zero,
 *	return the actual length in *lencopied.
 */
ENTRY(copyinstr)
	pushl	%esi
	pushl	%edi
	movl	_curpcb,%ecx
	movl	$cpystrflt,PCB_ONFAULT(%ecx)

	movl	12(%esp),%esi			/* %esi = from */
	movl	16(%esp),%edi			/* %edi = to */
	movl	20(%esp),%edx			/* %edx = maxlen */

	movl	$VM_MAXUSER_ADDRESS,%eax

	/* make sure 'from' is within bounds */
	subl	%esi,%eax
	jbe	cpystrflt

	/* restrict maxlen to <= VM_MAXUSER_ADDRESS-from */
	cmpl	%edx,%eax
	jae	1f
	movl	%eax,%edx
	movl	%eax,20(%esp)
1:
	incl	%edx
	cld

2:
	decl	%edx
	jz	3f

	lodsb
	stosb
	orb	%al,%al
	jnz	2b

	/* Success -- 0 byte reached */
	decl	%edx
	xorl	%eax,%eax
	jmp	cpystrflt_x
3:
	/* edx is zero - return ENAMETOOLONG or EFAULT */
	cmpl	$VM_MAXUSER_ADDRESS,%esi
	jae	cpystrflt
4:
	movl	$ENAMETOOLONG,%eax
	jmp	cpystrflt_x

cpystrflt:
	movl	$EFAULT,%eax

cpystrflt_x:
	/* set *lencopied and return %eax */
	movl	_curpcb,%ecx
	movl	$0,PCB_ONFAULT(%ecx)
	movl	20(%esp),%ecx
	subl	%edx,%ecx
	movl	24(%esp),%edx
	testl	%edx,%edx
	jz	1f
	movl	%ecx,(%edx)
1:
	popl	%edi
	popl	%esi
	ret


/*
 * copystr(from, to, maxlen, int *lencopied)
 */
ENTRY(copystr)
	pushl	%esi
	pushl	%edi

	movl	12(%esp),%esi			/* %esi = from */
	movl	16(%esp),%edi			/* %edi = to */
	movl	20(%esp),%edx			/* %edx = maxlen */
	incl	%edx
	cld
1:
	decl	%edx
	jz	4f
	lodsb
	stosb
	orb	%al,%al
	jnz	1b

	/* Success -- 0 byte reached */
	decl	%edx
	xorl	%eax,%eax
	jmp	6f
4:
	/* edx is zero -- return ENAMETOOLONG */
	movl	$ENAMETOOLONG,%eax

6:
	/* set *lencopied and return %eax */
	movl	20(%esp),%ecx
	subl	%edx,%ecx
	movl	24(%esp),%edx
	testl	%edx,%edx
	jz	7f
	movl	%ecx,(%edx)
7:
	popl	%edi
	popl	%esi
	ret

ENTRY(bcmp)
	pushl	%edi
	pushl	%esi
	movl	12(%esp),%edi
	movl	16(%esp),%esi
	movl	20(%esp),%edx
	xorl	%eax,%eax

	movl	%edx,%ecx
	shrl	$2,%ecx
	cld					/* compare forwards */
	repe
	cmpsl
	jne	1f

	movl	%edx,%ecx
	andl	$3,%ecx
	repe
	cmpsb
	je	2f
1:
	incl	%eax
2:
	popl	%esi
	popl	%edi
	ret


/*
 * Handling of special 386 registers and descriptor tables etc
 */
/* void lgdt(struct region_descriptor *rdp); */
ENTRY(lgdt)
	/* reload the descriptor table */
	movl	4(%esp),%eax
	lgdt	(%eax)

	/* flush the prefetch q */
	jmp	1f
	nop
1:
	/* reload "stale" selectors */
	movl	$KDSEL,%eax
	movl	%ax,%ds
	movl	%ax,%es
	movl	%ax,%ss

	/* reload code selector by turning return into intersegmental return */
	movl	(%esp),%eax
	pushl	%eax
#	movl	$KCSEL,4(%esp)
	movl	$8,4(%esp)
	lret

/*
 * void lidt(struct region_descriptor *rdp);
 */
ENTRY(lidt)
	movl	4(%esp),%eax
	lidt	(%eax)
	ret

/*
 * void lldt(u_short sel)
 */
ENTRY(lldt)
	lldt	4(%esp)
	ret

/*
 * void ltr(u_short sel)
 */
ENTRY(ltr)
	ltr	4(%esp)
	ret

/* ssdtosd(*ssdp,*sdp) */
ENTRY(ssdtosd)
	pushl	%ebx
	movl	8(%esp),%ecx
	movl	8(%ecx),%ebx
	shll	$16,%ebx
	movl	(%ecx),%edx
	roll	$16,%edx
	movb	%dh,%bl
	movb	%dl,%bh
	rorl	$8,%ebx
	movl	4(%ecx),%eax
	movw	%ax,%dx
	andl	$0xf0000,%eax
	orl	%eax,%ebx
	movl	12(%esp),%ecx
	movl	%edx,(%ecx)
	movl	%ebx,4(%ecx)
	popl	%ebx
	ret

/* load_cr0(cr0) */
ENTRY(load_cr0)
	movl	4(%esp),%eax
	movl	%eax,%cr0
	ret

/* rcr0() */
ENTRY(rcr0)
	movl	%cr0,%eax
	ret

/* rcr3() */
ENTRY(rcr3)
	movl	%cr3,%eax
	ret

/* void load_cr3(caddr_t cr3) */
ENTRY(load_cr3)
	movl	4(%esp),%eax
	movl	%eax,%cr3
	ret


/*****************************************************************************/
/* setjump, longjump                                                         */
/*****************************************************************************/

ENTRY(setjmp)
	movl	4(%esp),%eax
	movl	%ebx,(%eax)			/* save ebx */
	movl	%esp,4(%eax)			/* save esp */
	movl	%ebp,8(%eax)			/* save ebp */
	movl	%esi,12(%eax)			/* save esi */
	movl	%edi,16(%eax)			/* save edi */
	movl	(%esp),%edx			/* get rta */
	movl	%edx,20(%eax)			/* save eip */
	xorl	%eax,%eax			/* return(0); */
	ret

ENTRY(longjmp)
	movl	4(%esp),%eax
	movl	(%eax),%ebx			/* restore ebx */
	movl	4(%eax),%esp			/* restore esp */
	movl	8(%eax),%ebp			/* restore ebp */
	movl	12(%eax),%esi			/* restore esi */
	movl	16(%eax),%edi			/* restore edi */
	movl	20(%eax),%edx			/* get rta */
	movl	%edx,(%esp)			/* put in return frame */
	xorl	%eax,%eax			/* return(1); */
	incl	%eax
	ret

/*
 * Here for doing BB-profiling (gcc -a).
 * We rely on the "bbset" instead, but need a dummy function.
 */
NON_GPROF_ENTRY(__bb_init_func)
	movl	4(%esp),%eax
	movl	$1,(%eax)
	.byte	0xc3				/* avoid macro for `ret' */