⭐ 欢迎来到虫虫下载站! | 📦 资源下载 📁 资源专辑 ℹ️ 关于我们
⭐ 虫虫下载站

📄 子程序.txt

📁 51单片机子程序
💻 TXT
📖 第 1 页 / 共 3 页
字号:
EXP2:	MOV	A,R2	£?????êy?′??μ?μú?t1¤×÷??
	MOV	R5,A
	MOV	A,R3
	MOV	R6,A

MOV	A,R4
	MOV	R7,A
	MOV	C,1FH
	MOV	1EH,C
	LCALL	INT	£???μúò???è???
	MOV	A,R3
	JZ	EXP4
EXP3:	CLR	C	£?ê1?2êy??×??úR3??ó|ò???×??ú??êy
	RRC	A
	INC	R2
	CJNE	R2,#8,EXP3
EXP4:	MOV	R3,A
	JNB	1FH,EXP5
	CPL	A	£?2¢ó?21??±íê?
	INC	A
EXP5:	PUSH	ACC	£??Yê±±£′???
	LCALL	RLN	£???D?1????ˉ
	CPL	1FH
	SETB	F0
	LCALL	AS1	£??ó??êyμ?D?êy2?·?
	LCALL	MOV0	£???′???êyμ?D?êy2?·?
	LCALL	FPLN	£?í¨1y?à??ê???????êyμ?D?êy2?·?μ??Y
	DB	77H,0B1H,0C9H£?£±£?£3£μ£?£′?ᣱ£°-3

DB	7AH,0A1H,68H£?£1£?£?£μ£±£′?ᣱ£°-3
	DB	7CH,0E3H,4FH£?£°£?£°£μ£μ£′£1£μ
	DB	7EH,0F5H,0E7H£?£°£?£2£′£°£±£′
	DB	0,0B1H,72H£?£°£?£?£1£3£±£μ
	DB	1,80H,0	£?£±£?£°£°£°£°£°
	DB	40H	£??áê?
	POP	ACC	£?è?3???êyμ???êy2?·?
	ADD	A,R2	£?°′21???óμ??Yμ??×??é?
	MOV	R2,A
	CLR	1FH	£??Yμ?·?o??a?y
	LJMP	MOV0	£????Y′???[R0]?D

    £¨£2£′£?±êo?£o  £?£?£?£?    1|?ü£o??×??úê?áù?????¨μ?êy×a??3é??ê??ˉ??μ?êy

è??úì??t£o??×??ú?¨μ?êyμ??????μ?ú[R0]?D£?êy·??ú??1FH?D£???êy2?·?μ???êy?úA?D?£

3??úD??¢£o×a??3é??ê??ˉ??μ?êy?ú[R0]?D£¨èy×??ú£??£
ó°?ì×ê?′£oPSW?¢A?¢R2?¢R3?¢R4?¢??1FH  ????Dè?ó£o  £?×??ú

DTOF:	MOV	R2,A	£?°′??êyμ???êy3?ê??ˉ?×??
	MOV	A,@R0	£????¨μ?êy×÷?2êy
	MOV	R3,A
	INC	R0
	MOV	A,@R0
	MOV	R4,A
	DEC	R0
	LCALL	RLN	£???DD1????ˉ
	LJMP	MOV0	£?′??í?á1?μ?[R0]?D

    £¨£2£μ£?  ±êo?£o  £?£?£?£?    1|?ü£o??ê??ˉ??μ?êy×a??3é??×??ú?¨μ?êy

è??úì??t£o??ê??ˉ??μ?2ù×÷êy?ú[R0]?D?£
3??úD??¢£oOV=1ê±ò?3?£?OV=0ê±×a??3é1|£o?¨μ?êyμ??????μ?ú[R0]?D£¨??×??ú£?£?êy·?

?ú??1FH?D£?F0=1 ê±?a??êy£?CY=1ê±?aò?×??ú??êyò?×??úD?êy£?·??ò?a′?D?êy?£
ó°?ì×ê?′£oPSW?¢A?¢B?¢R2?¢R3?¢R4?¢??1FH    ????Dè?ó£o  £?×??ú

FTOD:	LCALL	MVR0	£???[R0]′??íμ?μúò?1¤×÷??
	MOV	A,R2
	JZ	FTD4	£??×???aá?£?′?D?êy
	JB	ACC.7,FTD4£??×???a?o£?′?D?êy
	SETB	C
	SUBB	A,#10H
	JC	FTD1
	SETB	OV	£??×??′óóú£±£?£?ò?3?
	RET
FTD1:	SETB	C
	MOV	A,R2
	SUBB	A,#8	£??×??′óóú£?·?£?
	JC	FTD3
FTD2:	MOV	B,#10H	£??×??′óóú£?£?°′??×??ú??êy×a??
	LCALL	FTD8

SETB	F0	£?éèá¢??×??ú??êy±ê??
	CLR	C
	CLR	OV
	RET
FTD3:	MOV	B,#8	£?°′ò?×??ú??êyò?×??úD?êy×a??
	LCALL	FTD8
	SETB	C	£?éèá¢ò?×??ú??êyò?×??úD?êy±ê??
	CLR	F0
	CLR	OV
	RET
FTD4:	MOV	B,#0	£?°′′?D?êy×a??
	LCALL	FTD8
	CLR	OV	£?éèá¢′?D?êy±ê??
	CLR	F0
	CLR	C
	RET
FTD8:	MOV	A,R2	£?°′1??¨μ???êy??êy??DDóò1?
	CJNE	A,B,FTD9
	MOV	A,R3	£?????×??ú?á1?′??íμ?[R0]?D
	MOV	@R0,A
	INC	R0
	MOV	A,R4
	MOV	@R0,A
	DEC	R0
	RET 	

FTD9:	CLR	C
	LCALL	RR1	£?óò1?ò?′?
	SJMP	FTD8

    £¨£2£?£?  ±êo?£o  £?£?£?£?    1|?ü£o??μ?£?£?£???×a??3é??ê??ˉ??μ?êy

è??úì??t£o??μ?£?£?£???2ù×÷êy?ú[R0]?D?£
3??úD??¢£o×a??3éμ???ê??ˉ??μ?êyè??ú[R0]?D?£
ó°?ì×ê?′£oPSW?¢A?¢B?¢R2??R7?¢??1DH??1FH  ????Dè?ó£o£?×??ú

BTOF:	INC	R0	£??D??ê?·??aá??£
	INC	R0
	MOV	A,@R0
	MOV	R7,A
	DEC	R0
	MOV	A,@R0
	MOV	R6,A
	DEC	R0
	ORL	A,R7
	JNZ	BTF0
	MOV	@R0,#41H£??aá?£?×a???áê??£
	RET
BTF0:	MOV	A,@R0

MOV	C,ACC.7
	MOV	1DH,C	£?±£′?êy·??£
	CLR	1FH	£?ò??????μ??DD×a???£
	MOV	C,ACC.6	£?à?3??×???a°????£
	MOV	ACC.7,C
	MOV	@R0,A
	JNC	BTF1
	ADD	A,#19	£?ê?·?D?óú£±£?£-£±£1£?
	JC	BTF2
	MOV	@R0,#41H£?D?óú£±£?£-£±£1ê±ò?£°???£
	INC	R0
	MOV	@R0,#0
	INC	R0
	MOV	@R0,#0
	DEC	R0
	DEC	R0
	RET
BTF1:	SUBB	A,#19
	JC	BTF2
	MOV	A,#3FH	£?′óóú£±£?£±£1ê±·a?¥?£
	MOV	C,1DH
	MOV	ACC.7,C
	MOV	@R0,A
	INC	R0
	MOV	@R0,#0FFH
	INC	R0

MOV	@R0,#0FFH
	DEC	R0
	DEC	R0
	RET
BTF2:	CLR	A	£?×?±???£?£?£????2êy×a??3éê?áù??????μ?êy?£
	MOV	R4,A
	MOV	R3,A
	MOV	R2,#10H	£??áéùá???×??ú?£
BTF3:	MOV	A,R7
	ADD	A,R7
	DA	A
	MOV	R7,A
	MOV	A,R6
	ADDC	A,R6
	DA	A
	MOV	R6,A
	MOV	A,R4
	RLC	A
	MOV	R4,A
	MOV	A,R3
	RLC	A
	MOV	R3,A
	DEC	R2
	JNB	ACC.7,BTF3£??±μ??2êy1????ˉ?£
	MOV	A,R6	£???éá??è??£
	ADD	A,#0B0H
	CLR	A
	ADDC	A,R4
	MOV	R4,A
	CLR	A

ADDC	A,R3
	MOV	R3,A
	JNC	BTF4
	MOV	R3,#80H
	INC	R2
BTF4:	MOV	DPTR,#BTFL£?×?±?2é±íμ?μ?ê??????×????ó|μ???μ?êy?£
	MOV	A,@R0
	ADD	A,#19	£?????±í????ò?á??£
	MOV	B,#3
	MUL	AB
	ADD	A,DPL
	MOV	DPL,A
	JNC	BTF5
	INC	DPH
BTF5:	CLR	A	£?2é±í?£
	MOVC	A,@A+DPTR
	MOV	C,ACC.6
	MOV	ACC.7,C
	MOV	R5,A
	MOV	A,#1
	MOVC	A,@A+DPTR
	MOV	R6,A
	MOV	A,#2
	MOVC	A,@A+DPTR
	MOV	R7,A
	LCALL	MUL1	£????×????ó|μ???μ?êyoí?2êy??ó|μ???μ?êy?à3??£

MOV	C,1DH	£?è?3?êy·??£
	MOV	1FH,C
	LJMP	MOV0	£?′??í×a???á1??£

   £¨£2£·£?  ±êo?£o  £?£?£?£?    1|?ü£o??ê??ˉ??μ?êy×a??3é??μ?£?£?£???

è??úì??t£o??ê??ˉ??μ?2ù×÷êy?ú[R0]?D?£
3??úD??¢£o×a??3éμ???μ?£?£?£???è??ú[R0]?D?£
ó°?ì×ê?′£oPSW?¢A?¢B?¢R2??R7?¢??1DH??1FH   ????Dè?ó£o£?×??ú

FTOB:	INC	R0
	MOV	A,@R0
	INC	R0
	ORL	A,@R0
	DEC	R0
	DEC	R0
	JNZ	FTB0
	MOV	@R0,#41H
	RET
FTB0:	MOV	A,@R0
	MOV	C,ACC.7
	MOV	1DH,C
	CLR	ACC.7
	MOV	@R0,A

LCALL	MVR0
	MOV	DPTR,#BFL0£??????μ′óóú?òμèóú£±ê±μ?2é±í?eμ??£
	MOV	B,#0	£?ê?μ?£°′??Y?£
	MOV	A,R2
	JNB	ACC.7,FTB1
	MOV	DPTR,#BTFL£??????μD?óú£±£?£-£?ê±μ?2é±í?eμ??£
	MOV	B,#0EDH	£?ê?μ?£-£±£1′??Y?£
	ADD	A,#16
	JNC	FTB1
	MOV	DPTR,#BFLN£??????μ′óóú?òμèóú£±£?£-£?ê±μ?2é±í?eμ??£
	MOV	B,#0FAH	£?ê?μ?£-£?′??Y?£
FTB1:	CLR	A	£?2é±í£??òμ?ò???±è′y×a????μ?êy′óμ???êy?Y?£
	MOVC	A,@A+DPTR
	MOV	C,ACC.6
	MOV	ACC.7,C
	MOV	R5,A
	MOV	A,#1
	MOVC	A,@A+DPTR

MOV	R6,A
	MOV	A,#2
	MOVC	A,@A+DPTR
	MOV	R7,A
	MOV	A,R5	£?oí′y×a????μ?êy±è???£
	CLR	C
	SUBB	A,R2
	JB	ACC.7,FTB2£?2??a?oêy?£	
	JNZ	FTB3
	MOV	A,R6
	CLR	C
	SUBB	A,R3
	JC	FTB2
	JNZ	FTB3
	MOV	A,R7
	CLR	C
	SUBB	A,R4
	JC	FTB2
	JNZ	FTB3
	MOV	R5,B	£??yo?ê?±í???Dμ?êy?£
	INC	R5	£??Y?óò??£
	MOV	R6,#10H	£??2êy?a£°?¤£±£°£°£°?£
	MOV	R7,#0
	SJMP	FTB6	£?′??í×a???á1??£
FTB2:	INC	DPTR	£?×?±?±í????ò????£
	INC	DPTR

INC	DPTR
	INC	B	£??Y?óò??£
	SJMP	FTB1	£?	
FTB3:	PUSH	B	£?±£′??Y?μ?£
	LCALL	DIV3	£??à3y£?μ?μ?ò????t??????μ?êyμ?′?D?êy?£
FTB4:	MOV	A,R2	£?è??×???£
	JZ	FTB5	£??aá??e£?
	CLR	C
	LCALL	RR1	£?óò1??£
	SJMP	FTB4
FTB5:	POP	ACC	£?è?3??Y?μ?£
	MOV	R5,A	£?×÷?aê???????μ?êyμ??×???£
	LCALL	HB2	£?×a???2êyμ?ê?·???oí°ù·????£
	MOV	R6,A
	LCALL	HB2	£?×a???2êyμ??§·???oííò·????£
	MOV	R7,A
	MOV	A,R3	£???éá??è??£
	RLC	A
	CLR	A
	ADDC	A,R7

DA	A
	MOV	R7,A
	CLR	A
	ADDC	A,R6
	DA	A
	MOV	R6,A
	JNC	FTB6
	MOV	R6,#10H
	INC	R5
FTB6:	INC	R0	£?′?·?×a???á1??£
	INC	R0
	MOV	A,R7
	MOV	@R0,A
	DEC	R0
	MOV	A,R6
	MOV	@R0,A
	DEC	R0
	MOV	A,R5
	MOV	C,1DH	£?è?3?êy·??£
	MOV	ACC.7,C
	MOV	@R0,A	
	RET
HB2:	MOV	A,R4	£??2êyà?′ó£±£°£°±??£
	MOV	B,#100
	MUL	AB
	MOV	R4,A
	MOV	A,B
	XCH	A,R3
	MOV	B,#100
	MUL	AB
	ADD	A,R3
	MOV	R3,A
	JNC	HB21

INC	B
HB21:	MOV	A,B	£?????êy2?·?×a??3é£?£?£????£
	MOV	B,#10
	DIV	AB
	SWAP	A
	ORL	A,B
	RET
BTFL:	DB	41H,0ECH,1EH	£?1.0000E-19
	DB	45H,93H,93H	£?1.0000E-18
	DB	48H,0B8H,78H	£?1.0000E-17
	DB	4BH,0E6H,96H	£?1.0000E-16
	DB	4FH,90H,1DH	£?1.0000E-15
	DB	52H,0B4H,25H	£?1.0000E-14
	DB	55H,0E1H,2EH	£?1.0000E-13
	DB	59H,8CH,0BDH	£?1.0000E-12
	DB	5CH,0AFH,0ECH	£?1.0000E-11
	DB	5FH,0DBH,0E7H	£?1.0000E-10
	DB	63H,89H,70H	£?1.0000E-9

DB	66H,0ABH,0CCH	£?1.0000E-8
	DB	69H,0D6H,0C0H	£?1.0000E-7
BFLN:	DB	6DH,86H,38H	£?1.0000E-6
	DB	70H,0A7H,0C6H	£?1.0000E-5
	DB	73H,0D1H,0B7H	£?1.0000E-4
	DB	77H,83H,12H	£?1.0000E-3
	DB	7AH,0A3H,0D7H	£?1.0000E-2
	DB	7DH,0CCH,0CDH	£?1.0000E-1
BFL0:	DB	1,80H,00H	£?1.0000
	DB	4,0A0H,00H	£?1.0000E1
	DB	7,0C8H,00H	£?1.0000E2
	DB	0AH,0FAH,00H	£?1.0000E3
	DB	0EH,9CH,40H	£?1.0000E4
	DB	11H,0C3H,50H	£?1.0000E5
	DB	14H,0F4H,24H	£?1.0000E6

DB	18H,98H,97H	£?1.0000E7
	DB	1BH,0BEH,0BCH	£?1.0000E8
	DB	1EH,0EEH,6BH	£?1.0000E9
	DB	22H,95H,03H	£?1.0000E10
	DB	25H,0BAH,44H	£?1.0000E11
	DB	28H,0E8H,0D5H	£?1.0000E12
	DB	2CH,91H,85H	£?1.0000E13
	DB	2FH,0B5H,0E6H	£?1.0000E14
	DB	32H,0E3H,60H	£?1.0000E15
	DB	36H,8EH,1CH	£?1.0000E16
	DB	39H,31H,0A3H	£?1.0000E17
	DB	3CH,0DEH,0BH	£?1.0000E18
	DB	40H,8AH,0C7H	£?1.0000E19

    £¨£2£?£?  ±êo?£o  £?£?£?£ó    1|?ü£o??μ?óà?òoˉêy

è??úì??t£o2ù×÷êy?ú[R0]?D?£
3??úD??¢£o?á1?è??ú[R0]?D?£
ó°?ì×ê?′£oDPTR?¢PSW?¢A?¢B?¢R2??R7?¢??1DH??1FH  ????Dè?ó£o  £?×??ú

FCOS:	LCALL	FABS	£?COS(-X) = COS X
	MOV	R5,#1	£?3£êy1.5708£¨|D£ˉ£2£?
	MOV	R6,#0C9H
	MOV	R7,#10H
	CLR	1EH
	LCALL	MVR0
	CLR	F0
	LCALL	AS1	£?£?£?£¨|D£ˉ£2£?
	LCALL	MOV0	£?±£′??á1?£??ó×???DD????μ?FSIN3ìDò

    £¨£2£1£?  ±êo?£o  £?£ó£é£?    1|?ü£o??μ??y?òoˉêy

è??úì??t£o2ù×÷êy?ú[R0]?D?£
3??úD??¢£o?á1?è??ú[R0]?D?£
ó°?ì×ê?′£oDPTR?¢PSW?¢A?¢B?¢R2??R7?¢??1DH??1FH  ????Dè?ó£o  £?×??ú

FSIN:	MOV	A,@R0
	MOV	C,ACC.7
	MOV	1DH,C	£?±£′?×?±?á?μ?·?o?
	CLR	ACC.7	£?í3ò?°′?yêy????
	MOV	@R0,A
	LCALL	MVR0	£???[R0]′??íμ?μúò?1¤×÷??
	MOV	R5,#0	£??μêy£°£?£?£3£?£?£2£·£¨£2£ˉ|D£?
	MOV	R6,#0A2H
	MOV	R7,#0FAH
	CLR	1EH
	LCALL	MUL1	£??à3?£?×?±?á?°′£¨|D£ˉ£2£?1?ò??ˉ
	MOV	A,R2	£????á1??′??μ?μú?t??
	MOV	R5,A
	MOV	A,R3
	MOV	R6,A
	MOV	A,R4
	MOV	R7,A
	LCALL	INT	£?μúò???è???£???μ??ó?TD??¢
	MOV	A,R2
	JZ	SIN2
SIN1:	CLR	C	£?????μ??ó?Têy×a??3é?¨μ??ó?Têy

LCALL	RR1
	CJNE	R2,#10H,SIN1
	MOV	A,R4
	JNB	ACC.1,SIN2
	CPL	1DH	£???óúμúèy?¢???ó?T£??á1?è?·′
SIN2:	JB	ACC.0,SIN3
	CPL	1FH	£???óúμúò??¢èy?ó?T£??±?ó?ó1?ò??ˉμ?D?êy
	SJMP	SIN4
SIN3:	MOV	A,R4	£???óúμú?t?¢???ó?T£?×?±??ó??21êy
	INC	A
	MOV	R4,A
	JNZ	SIN4
	INC	R3
SIN4:	LCALL	RLN	£?1????ˉ
	SETB	F0
	LCALL	AS1	£??ó×?±?á?1éò??ˉμèD§?μ
	LCALL	MOV0	£???′?
	LCALL	FPLN	£?ó??à??ê??????y?ò?μ
	DB	7DH,93H,28H£?£°£?£°£·£±£?£μ
	DB	41H,0,0	£?£°

DB	80H,0A4H,64H£?£-£°£?£?£′£2£±£μ
	DB	41H,0,0	£?£°
	DB	1,0C9H,2£?£±£?£μ£·£°£′
	DB	41H,0,0	£?£°
	DB	40H	£??áê?
	MOV	A,@R0	£??á1?μ??????μ3?1y£±£?£°£°?e£?
	JZ	SIN5
	JB	ACC.6,SIN5
	INC	R0	£??????μ°′£±£?£°£°·a?¥
	MOV	@R0,#80H
	INC	R0
	MOV	@R0,#0
	DEC	R0
	DEC	R0
	MOV	A,#1
SIN5:	MOV	C,1DH	£???êy·??′è??á1??D
	MOV	ACC.7,C
	MOV	@R0,A
	RET

    £¨£3£°£?  ±êo?£o  £?£á£?£?    1|?ü£o??μ?·′?y?Doˉêy

è??úì??t£o2ù×÷êy?ú[R0]?D?£

3??úD??¢£o?á1?è??ú[R0]?D?£
ó°?ì×ê?′£oDPTR?¢PSW?¢A?¢B?¢R2??R7?¢??1CH??1FH ????Dè?ó£o£·×??ú

FATN:	MOV	A,@R0
	MOV	C,ACC.7
	MOV	1DH,C	£?±£′?×?±?á?êy·?
	CLR	ACC.7	£?×?±?á?è??????μ
	MOV	@R0,A
	CLR	1CH	£????óóà????±ê??
	JB	ACC.6,ATN1£?×?±?á??a′?D?êy·?£?
	JZ	ATN1
	SETB	1CH	£??????óóà????±ê??
	LCALL	FRCP	£?í¨1yμ1êy????£?×a??3é′?D?êy
ATN1:	LCALL	FPLN	£?í¨1y?à??ê?????£?????·′?y?Doˉêy?μ
	DB	0FCH,0E4H,91H£?£-£°£?£°£μ£μ£?£°£2
	DB	7FH,8FH,37H£?£°£?£2£·£1£2£2

DB	0FFH,0EDH,0E0H£?£-£°£?£′£?£′£?£°
	DB	7BH,0E8H,77H£?£°£?£°£2£?£3£·£·
	DB	0,0FFH,68H£?£°£?£1£1£·£·
	DB	72H,85H,0ECH£?£3£?£±£1£3£°?ᣱ£°-5
	DB	40H	£??áê?
	JNB	1CH,ATN2£?Dèòa?óóà????·?£?
	CPL	1FH	£?×?±?????±ê??
	MOV	C,1FH
	MOV	F0,C	£?3£êy£±£?£μ£·£°£?£¨|D£ˉ£2£?
	MOV	R5,#1
	MOV	R6,#0C9H
	MOV	R7,#10H
	LCALL	AS1	£??óóà????
	LCALL	MOV0	£???′?
ATN2:	MOV	A,@R0	£??′è??á1?μ?êy·?
	MOV	C,1DH
	MOV	ACC.7,C
	MOV	@R0,A
	RET


    £¨£3£±£?  ±êo?£o  £ò£?£?£?    1|?ü£o??μ????èêy×a??3é??μ??èêy

è??úì??t£o??μ????èêy?ú[R0]?D?£
3??úD??¢£o×a??3éμ???μ??èêyè??ú[R0]?D?£
ó°?ì×ê?′£oPSW?¢A?¢B?¢R2??R7?¢??1EH?¢1FH  ????Dè?ó£o£?×??ú

RTOD:	MOV	R5,#6	£??μêy£¨£±£?£°£ˉ|D£?′??íμ?μú?t1¤×÷??
	MOV	R6,#0E5H
	MOV	R7,#2FH
	SJMP	DR	£?í¨1y3?·¨??DD×a??

    £¨£3£2£?  ±êo?£o  £?£?£?£ò    1|?ü£o??μ??èêy×a??3é??μ????èêy

è??úì??t£o??μ??èêy?ú[R0]?D?£
3??úD??¢£o×a??3éμ???μ????èêyè??ú[R0]?D?£
ó°?ì×ê?′£oPSW?¢A?¢B?¢R2??R7?¢??1EH?¢1FH  ????Dè?ó£o£?×??ú

DTOR:	MOV	R5,#0FBH£??μêy£¨|D£ˉ£±£?£°£?′??íμ?μú?t1¤×÷??
	MOV	R6,#8EH
	MOV	R7,#0FAH
DR:	LCALL	MVR0	£???[R0]′??íμ?μúò?1¤×÷??
	CLR	1EH	£??μêy?a?y
	LCALL	MUL1	£?í¨1y3?·¨??DD×a??
	LJMP	MOV0	£??á1?′??íμ?[R0]?D
	END

⌨️ 快捷键说明

复制代码 Ctrl + C
搜索代码 Ctrl + F
全屏模式 F11
切换主题 Ctrl + Shift + D
显示快捷键 ?
增大字号 Ctrl + =
减小字号 Ctrl + -