lib1funcs.asm

gcc-you can use this code to learn something about gcc, and inquire further into linux,

	add	dividend, work
Lover6:
	mov	curbit, ip
	mov	work, #2
	ror	curbit, work
	tst	overdone, curbit
	beq	Lover7
	lsr	work, divisor, #2
	add	dividend, work
Lover7:
	mov	curbit, ip
	mov	work, #1
	ror	curbit, work
	tst	overdone, curbit
	beq	Lgot_result
	lsr	work, divisor, #1
	add	dividend, work
  .endif
Lgot_result:
.endm	
/* ------------------------------------------------------------------------ */
/*		Start of the Real Functions				    */
/* ------------------------------------------------------------------------ */
#ifdef L_udivsi3

	FUNC_START udivsi3

#ifdef __thumb__

	cmp	divisor, #0
	beq	Ldiv0
	mov	curbit, #1
	mov	result, #0
	
	push	{ work }
	cmp	dividend, divisor
	blo	Lgot_result

	THUMB_DIV_MOD_BODY 0
	
	mov	r0, result
	pop	{ work }
	RET

#else /* ARM version.  */
	
	cmp	divisor, #0
	beq	Ldiv0
	mov	curbit, #1
	mov	result, #0
	cmp	dividend, divisor
	blo	Lgot_result
	
	ARM_DIV_MOD_BODY 0
	
	mov	r0, result
	RET	

#endif /* ARM version */

	FUNC_END udivsi3

#endif /* L_udivsi3 */
/* ------------------------------------------------------------------------ */
#ifdef L_umodsi3

	FUNC_START umodsi3

#ifdef __thumb__

	cmp	divisor, #0
	beq	Ldiv0
	mov	curbit, #1
	cmp	dividend, divisor
	bhs	Lover10
	RET	

Lover10:
	push	{ work }

	THUMB_DIV_MOD_BODY 1
	
	pop	{ work }
	RET
	
#else  /* ARM version.  */
	
	cmp	divisor, #0
	beq	Ldiv0
	cmp     divisor, #1
	cmpne	dividend, divisor
	moveq   dividend, #0
	RETc(lo)
	mov	curbit, #1

	ARM_DIV_MOD_BODY 1
	
	RET	

#endif /* ARM version.  */
	
	FUNC_END umodsi3

#endif /* L_umodsi3 */
/* ------------------------------------------------------------------------ */
#ifdef L_divsi3

	FUNC_START divsi3	

#ifdef __thumb__
	cmp	divisor, #0
	beq	Ldiv0
	
	push	{ work }
	mov	work, dividend
	eor	work, divisor		@ Save the sign of the result.
	mov	ip, work
	mov	curbit, #1
	mov	result, #0
	cmp	divisor, #0
	bpl	Lover10
	neg	divisor, divisor	@ Loops below use unsigned.
Lover10:
	cmp	dividend, #0
	bpl	Lover11
	neg	dividend, dividend
Lover11:
	cmp	dividend, divisor
	blo	Lgot_result

	THUMB_DIV_MOD_BODY 0
	
	mov	r0, result
	mov	work, ip
	cmp	work, #0
	bpl	Lover12
	neg	r0, r0
Lover12:
	pop	{ work }
	RET

#else /* ARM version.  */
	
	eor	ip, dividend, divisor		@ Save the sign of the result.
	mov	curbit, #1
	mov	result, #0
	cmp	divisor, #0
	rsbmi	divisor, divisor, #0		@ Loops below use unsigned.
	beq	Ldiv0
	cmp	dividend, #0
	rsbmi	dividend, dividend, #0
	cmp	dividend, divisor
	blo	Lgot_result

	ARM_DIV_MOD_BODY 0
	
	mov	r0, result
	cmp	ip, #0
	rsbmi	r0, r0, #0
	RET	

#endif /* ARM version */
	
	FUNC_END divsi3

#endif /* L_divsi3 */
/* ------------------------------------------------------------------------ */
#ifdef L_modsi3

	FUNC_START modsi3

#ifdef __thumb__

	mov	curbit, #1
	cmp	divisor, #0
	beq	Ldiv0
	bpl	Lover10
	neg	divisor, divisor		@ Loops below use unsigned.
Lover10:
	push	{ work }
	@ Need to save the sign of the dividend, unfortunately, we need
	@ work later on.  Must do this after saving the original value of
	@ the work register, because we will pop this value off first.
	push	{ dividend }
	cmp	dividend, #0
	bpl	Lover11
	neg	dividend, dividend
Lover11:
	cmp	dividend, divisor
	blo	Lgot_result

	THUMB_DIV_MOD_BODY 1
		
	pop	{ work }
	cmp	work, #0
	bpl	Lover12
	neg	dividend, dividend
Lover12:
	pop	{ work }
	RET	

#else /* ARM version.  */
	
	cmp	divisor, #0
	rsbmi	divisor, divisor, #0		@ Loops below use unsigned.
	beq	Ldiv0
	@ Need to save the sign of the dividend, unfortunately, we need
	@ ip later on; this is faster than pushing lr and using that.
	str	dividend, [sp, #-4]!
	cmp	dividend, #0			@ Test dividend against zero
	rsbmi	dividend, dividend, #0		@ If negative make positive
	cmp	dividend, divisor		@ else if zero return zero
	blo	Lgot_result			@ if smaller return dividend
	mov	curbit, #1

	ARM_DIV_MOD_BODY 1

	ldr	ip, [sp], #4
	cmp	ip, #0
	rsbmi	dividend, dividend, #0
	RET	

#endif /* ARM version */
	
	FUNC_END modsi3

#endif /* L_modsi3 */
/* ------------------------------------------------------------------------ */
#ifdef L_dvmd_tls

	FUNC_START div0

	RET

	SIZE	(__div0)
	
#endif /* L_divmodsi_tools */
/* ------------------------------------------------------------------------ */
#ifdef L_dvmd_lnx
@ GNU/Linux division-by zero handler.  Used in place of L_dvmd_tls

/* Constants taken from <asm/unistd.h> and <asm/signal.h> */
#define SIGFPE	8
#define __NR_SYSCALL_BASE	0x900000
#define __NR_getpid			(__NR_SYSCALL_BASE+ 20)
#define __NR_kill			(__NR_SYSCALL_BASE+ 37)

	FUNC_START div0

	stmfd	sp!, {r1, lr}
	swi	__NR_getpid
	cmn	r0, #1000
	ldmhsfd	sp!, {r1, pc}RETCOND	@ not much we can do
	mov	r1, #SIGFPE
	swi	__NR_kill
#ifdef __THUMB_INTERWORK__
	ldmfd	sp!, {r1, lr}
	bx	lr
#else
	ldmfd	sp!, {r1, pc}RETCOND
#endif

	SIZE 	(__div0)
	
#endif /* L_dvmd_lnx */
/* ------------------------------------------------------------------------ */
/* These next two sections are here despite the fact that they contain Thumb 
   assembler because their presence allows interworked code to be linked even
   when the GCC library is this one.  */
		
/* Do not build the interworking functions when the target architecture does 
   not support Thumb instructions.  (This can be a multilib option).  */
#if defined L_call_via_rX && (defined __ARM_ARCH_4T__ || defined __ARM_ARCH_5T__ || defined __ARM_ARCH_5TE__)

/* These labels & instructions are used by the Arm/Thumb interworking code. 
   The address of function to be called is loaded into a register and then 
   one of these labels is called via a BL instruction.  This puts the 
   return address into the link register with the bottom bit set, and the 
   code here switches to the correct mode before executing the function.  */
	
	.text
	.align 0
        .force_thumb

.macro call_via register
	THUMB_FUNC_START _call_via_\register

	bx	\register
	nop

	SIZE	(_call_via_\register)
.endm

	call_via r0
	call_via r1
	call_via r2
	call_via r3
	call_via r4
	call_via r5
	call_via r6
	call_via r7
	call_via r8
	call_via r9
	call_via sl
	call_via fp
	call_via ip
	call_via sp
	call_via lr

#endif /* L_call_via_rX */
/* ------------------------------------------------------------------------ */
/* Do not build the interworking functions when the target architecture does 
   not support Thumb instructions.  (This can be a multilib option).  */
#if defined L_interwork_call_via_rX && (defined __ARM_ARCH_4T__ || defined __ARM_ARCH_5T__ || defined __ARM_ARCH_5TE__)

/* These labels & instructions are used by the Arm/Thumb interworking code,
   when the target address is in an unknown instruction set.  The address 
   of function to be called is loaded into a register and then one of these
   labels is called via a BL instruction.  This puts the return address 
   into the link register with the bottom bit set, and the code here 
   switches to the correct mode before executing the function.  Unfortunately
   the target code cannot be relied upon to return via a BX instruction, so
   instead we have to store the resturn address on the stack and allow the
   called function to return here instead.  Upon return we recover the real
   return address and use a BX to get back to Thumb mode.  */
	
	.text
	.align 0

	.code   32
	.globl _arm_return
_arm_return:		
	ldmia 	r13!, {r12}
	bx 	r12
	.code   16

.macro interwork register					
	.code   16

	THUMB_FUNC_START _interwork_call_via_\register

	bx 	pc
	nop
	
	.code   32
	.globl .Lchange_\register
.Lchange_\register:
	tst	\register, #1
	stmeqdb	r13!, {lr}
	adreq	lr, _arm_return
	bx	\register

	SIZE	(_interwork_call_via_\register)
.endm
	
	interwork r0
	interwork r1
	interwork r2
	interwork r3
	interwork r4
	interwork r5
	interwork r6
	interwork r7
	interwork r8
	interwork r9
	interwork sl
	interwork fp
	interwork ip
	interwork sp
	
	/* The LR case has to be handled a little differently...  */
	.code 16

	THUMB_FUNC_START _interwork_call_via_lr

	bx 	pc
	nop
	
	.code 32
	.globl .Lchange_lr
.Lchange_lr:
	tst	lr, #1
	stmeqdb	r13!, {lr}
	mov	ip, lr
	adreq	lr, _arm_return
	bx	ip
	
	SIZE	(_interwork_call_via_lr)
	
#endif /* L_interwork_call_via_rX */