libgcc.s

linux下的gcc编译器

/*  -*- Mode: Asm -*-  */
/* Copyright (C) 1998, 1999, 2000 Free Software Foundation, Inc.
   Contributed by Denis Chertykov <[e-mail]>

This file is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 2, or (at your option) any
later version.

In addition to the permissions in the GNU General Public License, the
Free Software Foundation gives you unlimited permission to link the
compiled version of this file into combinations with other programs,
and to distribute those combinations without any restriction coming
from the use of this file.  (The General Public License restrictions
do apply in other respects; for example, they cover modification of
the file, and distribution when not linked into a combine
executable.)

This file is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; see the file COPYING.  If not, write to
the Free Software Foundation, 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.  */

#define __zero_reg__ r1
#define __tmp_reg__ r0
#define __SREG__ 0x3f
#define __SP_H__ 0x3e
#define __SP_L__ 0x3d

/* Most of the functions here are called directly from avr.md
   patterns, instead of using the standard libcall mechanisms.
   This can make better code because GCC knows exactly which
   of the call-used registers (not all of them) are clobbered.  */

	.section .text.libgcc, "ax", @progbits

	.macro	mov_l  r_dest, r_src
#if defined (__AVR_ENHANCED__)
	movw	\r_dest, \r_src
#else
	mov	\r_dest, \r_src
#endif
	.endm

	.macro	mov_h  r_dest, r_src
#if defined (__AVR_ENHANCED__)
	; empty
#else
	mov	\r_dest, \r_src
#endif
	.endm

/* Note: mulqi3, mulhi3 are open-coded on the enhanced core.  */
#if !defined (__AVR_ENHANCED__)
/*******************************************************
               Multiplication  8 x 8
*******************************************************/
#if defined (L_mulqi3)

#define	r_arg2	r22		/* multiplicand */
#define	r_arg1 	r24		/* multiplier */
#define r_res	__tmp_reg__	/* result */

	.global	__mulqi3
	.func	__mulqi3
__mulqi3:
	clr	r_res		; clear result
__mulqi3_loop:
	sbrc	r_arg1,0
	add	r_res,r_arg2
	add	r_arg2,r_arg2	; shift multiplicand
	breq	__mulqi3_exit	; while multiplicand != 0
	lsr	r_arg1		; 
	brne	__mulqi3_loop	; exit if multiplier = 0
__mulqi3_exit:	
	mov	r_arg1,r_res	; result to return register
	ret

#undef r_arg2  
#undef r_arg1  
#undef r_res   
	
.endfunc
#endif 	/* defined (L_mulqi3) */

#if defined (L_mulqihi3)
	.global	__mulqihi3
	.func	__mulqihi3
__mulqihi3:
	clr	r25
	sbrc	r24, 7
	dec	r25
	clr	r23
	sbrc	r22, 7
	dec	r22
	rjmp	__mulhi3
	.endfunc
#endif /* defined (L_mulqihi3) */

#if defined (L_umulqihi3)
	.global	__umulqihi3
	.func	__umulqihi3
__umulqihi3:
	clr	r25
	clr	r23
	rjmp	__mulhi3
	.endfunc
#endif /* defined (L_umulqihi3) */

/*******************************************************
               Multiplication  16 x 16
*******************************************************/
#if defined (L_mulhi3)
#define	r_arg1L	r24		/* multiplier Low */
#define	r_arg1H	r25		/* multiplier High */
#define	r_arg2L	r22		/* multiplicand Low */
#define	r_arg2H	r23		/* multiplicand High */
#define r_resL	__tmp_reg__	/* result Low */
#define r_resH  r21		/* result High */

	.global	__mulhi3
	.func	__mulhi3
__mulhi3:
	clr	r_resH		; clear result
	clr	r_resL		; clear result
__mulhi3_loop:
	sbrs	r_arg1L,0
	rjmp	__mulhi3_skip1
	add	r_resL,r_arg2L	; result + multiplicand
	adc	r_resH,r_arg2H
__mulhi3_skip1:	
	add	r_arg2L,r_arg2L	; shift multiplicand
	adc	r_arg2H,r_arg2H

	cp	r_arg2L,__zero_reg__
	cpc	r_arg2H,__zero_reg__
	breq	__mulhi3_exit	; while multiplicand != 0

	lsr	r_arg1H		; gets LSB of multiplier
	ror	r_arg1L
	sbiw	r_arg1L,0
	brne	__mulhi3_loop	; exit if multiplier = 0
__mulhi3_exit:
	mov	r_arg1H,r_resH	; result to return register
	mov	r_arg1L,r_resL
	ret

#undef r_arg1L
#undef r_arg1H
#undef r_arg2L
#undef r_arg2H
#undef r_resL 	
#undef r_resH 

.endfunc
#endif /* defined (L_mulhi3) */
#endif /* !defined (__AVR_ENHANCED__) */

#if defined (L_mulhisi3)
	.global	__mulhisi3
	.func	__mulhisi3
__mulhisi3:
	mov_l	r18, r24
	mov_h	r19, r25
	clr	r24
	sbrc	r23, 7
	dec	r24
	mov	r25, r24
	clr	r20
	sbrc	r19, 7
	dec	r20
	mov	r21, r20
	rjmp	__mulsi3
	.endfunc
#endif /* defined (L_mulhisi3) */

#if defined (L_umulhisi3)
	.global	__umulhisi3
	.func	__umulhisi3
__umulhisi3:
	mov_l	r18, r24
	mov_h	r19, r25
	clr	r24
	clr	r25
	clr	r20
	clr	r21
	rjmp	__mulsi3
	.endfunc
#endif /* defined (L_umulhisi3) */

#if defined (L_mulsi3)
/*******************************************************
               Multiplication  32 x 32
*******************************************************/
#define r_arg1L  r22		/* multiplier Low */
#define r_arg1H  r23
#define	r_arg1HL r24
#define	r_arg1HH r25		/* multiplier High */


#define	r_arg2L  r18		/* multiplicand Low */
#define	r_arg2H  r19	
#define	r_arg2HL r20
#define	r_arg2HH r21		/* multiplicand High */
	
#define r_resL	 r26		/* result Low */
#define r_resH   r27
#define r_resHL	 r30
#define r_resHH  r31		/* result High */

	
	.global	__mulsi3
	.func	__mulsi3
__mulsi3:
#if defined (__AVR_ENHANCED__)
	mul	r_arg1L, r_arg2L
	movw	r_resL, r0
	mul	r_arg1H, r_arg2H
	movw	r_resHL, r0
	mul	r_arg1HL, r_arg2L
	add	r_resHL, r0
	adc	r_resHH, r1
	mul	r_arg1L, r_arg2HL
	add	r_resHL, r0
	adc	r_resHH, r1
	mul	r_arg1HH, r_arg2L
	add	r_resHH, r0
	mul	r_arg1HL, r_arg2H
	add	r_resHH, r0
	mul	r_arg1H, r_arg2HL
	add	r_resHH, r0
	mul	r_arg1L, r_arg2HH
	add	r_resHH, r0
	clr	r_arg1HH	; use instead of __zero_reg__ to add carry
	mul	r_arg1H, r_arg2L
	add	r_resH, r0
	adc	r_resHL, r1
	adc	r_resHH, r_arg1HH ; add carry
	mul	r_arg1L, r_arg2H
	add	r_resH, r0
	adc	r_resHL, r1
	adc	r_resHH, r_arg1HH ; add carry
	movw	r_arg1L, r_resL
	movw	r_arg1HL, r_resHL
	clr	r1		; __zero_reg__ clobbered by "mul"
	ret
#else
	clr	r_resHH		; clear result
	clr	r_resHL		; clear result
	clr	r_resH		; clear result
	clr	r_resL		; clear result
__mulsi3_loop:
	sbrs	r_arg1L,0
	rjmp	__mulsi3_skip1
	add	r_resL,r_arg2L		; result + multiplicand
	adc	r_resH,r_arg2H
	adc	r_resHL,r_arg2HL
	adc	r_resHH,r_arg2HH
__mulsi3_skip1:
	add	r_arg2L,r_arg2L		; shift multiplicand
	adc	r_arg2H,r_arg2H
	adc	r_arg2HL,r_arg2HL
	adc	r_arg2HH,r_arg2HH
	
	lsr	r_arg1HH	; gets LSB of multiplier
	ror	r_arg1HL
	ror	r_arg1H
	ror	r_arg1L
	brne	__mulsi3_loop
	sbiw	r_arg1HL,0
	cpc	r_arg1H,r_arg1L
	brne	__mulsi3_loop		; exit if multiplier = 0
__mulsi3_exit:
	mov	r_arg1HH,r_resHH	; result to return register
	mov	r_arg1HL,r_resHL
	mov	r_arg1H,r_resH
	mov	r_arg1L,r_resL
	ret
#endif /* !defined (__AVR_ENHANCED__) */
#undef r_arg1L 
#undef r_arg1H 
#undef r_arg1HL
#undef r_arg1HH
             
             
#undef r_arg2L 
#undef r_arg2H 
#undef r_arg2HL
#undef r_arg2HH
             
#undef r_resL  
#undef r_resH  
#undef r_resHL 
#undef r_resHH 

.endfunc
#endif /* defined (L_mulsi3) */
	
/*******************************************************
       Division 8 / 8 => (result + remainder)
*******************************************************/
#define	r_rem	r25	/* remainder */
#define	r_arg1	r24	/* dividend, quotient */
#define	r_arg2	r22	/* divisor */
#define	r_cnt	r23	/* loop count */

#if defined (L_udivmodqi4)
	.global	__udivmodqi4
	.func	__udivmodqi4
__udivmodqi4:
	sub	r_rem,r_rem	; clear remainder and carry
	ldi	r_cnt,9		; init loop counter
	rjmp	__udivmodqi4_ep	; jump to entry point
__udivmodqi4_loop:
	rol	r_rem		; shift dividend into remainder
	cp	r_rem,r_arg2	; compare remainder & divisor
	brcs	__udivmodqi4_ep	; remainder <= divisor
	sub	r_rem,r_arg2	; restore remainder
__udivmodqi4_ep:
	rol	r_arg1		; shift dividend (with CARRY)
	dec	r_cnt		; decrement loop counter
	brne	__udivmodqi4_loop
	com	r_arg1		; complement result 
				; because C flag was complemented in loop
	ret
	.endfunc
#endif /* defined (L_udivmodqi4) */

#if defined (L_divmodqi4)
	.global	__divmodqi4
	.func	__divmodqi4
__divmodqi4:
        bst     r_arg1,7	; store sign of dividend
        mov     __tmp_reg__,r_arg1
        eor     __tmp_reg__,r_arg2; r0.7 is sign of result
        sbrc	r_arg1,7
	neg     r_arg1		; dividend negative : negate
        sbrc	r_arg2,7
	neg     r_arg2		; divisor negative : negate
	rcall	__udivmodqi4	; do the unsigned div/mod
	brtc	__divmodqi4_1
	neg	r_rem		; correct remainder sign
__divmodqi4_1:
	sbrc	__tmp_reg__,7
	neg	r_arg1		; correct result sign
__divmodqi4_exit:
	ret
	.endfunc
#endif /* defined (L_divmodqi4) */

#undef r_rem
#undef r_arg1
#undef r_arg2
#undef r_cnt
	
		
/*******************************************************
       Division 16 / 16 => (result + remainder)
*******************************************************/
#define	r_remL	r26	/* remainder Low */
#define	r_remH	r27	/* remainder High */

/* return: remainder */
#define	r_arg1L	r24	/* dividend Low */
#define	r_arg1H	r25	/* dividend High */

/* return: quotient */
#define	r_arg2L	r22	/* divisor Low */
#define	r_arg2H	r23	/* divisor High */
	
#define	r_cnt	r21	/* loop count */

#if defined (L_udivmodhi4)
	.global	__udivmodhi4
	.func	__udivmodhi4
__udivmodhi4:
	sub	r_remL,r_remL
	sub	r_remH,r_remH	; clear remainder and carry
	ldi	r_cnt,17	; init loop counter
	rjmp	__udivmodhi4_ep	; jump to entry point
__udivmodhi4_loop:
        rol	r_remL		; shift dividend into remainder
	rol	r_remH
        cp	r_remL,r_arg2L	; compare remainder & divisor
	cpc	r_remH,r_arg2H