A51中怎样写切bank的程序 - 编程论坛

#2

zaixuexi2012-01-18 14:34

一般我遇到这种问题会怎么做？
第一步：google
http://www.
http://hi.baidu.com/fendou_mo/blog/item/be184821815f825d9922ed12.html
第二步:查keil c手册

#3

insight19822012-01-19 16:43

谢谢，
上面的那个例子是C语言写的
我编译C的例子是可以成功的
但是汇编的没有试成功，而且我是按照相同的设置

#4

GoldenSpider2012-02-09 21:36

USING Assembler Statement
Arguments USING expression

Description The USING statement specifies the register bank (0-3) expression to use for encoding the >AR0-AR7 registers. The register bank selected is noted in the object file and the memory area is reserved by the linker.

Some 8051 instructions (like PUSH and POP) allow only absolute addresses to be used. The assembler replaces absolute registers (AR0-AR7) with the physical address of the register in the current register bank. So, while the instruction PUSH R0 is not valid, PUSH AR0 is valid. However, the assembler must know which register bank is used so that the correct physical address is calculated. This is the purpose for the USING statement.

The USING statement does not generate any code to switch the current register bank. The assembler program must select the correct register bank. For example, the following code selects register bank 2:

PUSH    PSW               ; save the current register bank
MOV     PSW, #(2 SHL 3)   ; set register bank 2
.
.
.
POP     PSW               ; restore saved register bank
The physical address is calculated as follows:

(register bank × 8) + register

下面写了个例子

程序代码：

ORG 0
MOV     SP,#2FH
;=======================================================
PUSH    PSW             ; save the current register bank
MOV     PSW, #(2 SHL 3) ; set register bank 2
MOV     R2,#12H         ; 写入R2到bank 2
MOV     R7,#34H         ; 写入R7到bank 2
;-----------------------
USING   2               ; select register bank 2
PUSH    AR2             ; push R2 in bank 2 (address 12h)
PUSH    AR7             ; push R7 in bank 2 (address 17h)

POP     AR7
POP     AR2
;-----------------------
POP     PSW             ; restore saved register bank

;=======================================================
PUSH    PSW             ; save the current register bank
MOV     PSW, #(3 SHL 3) ; set register bank 3
MOV     R2,#12H         ; 写入R2到bank 3
MOV     R7,#34H         ; 写入R7到bank 3
;-----------------------
USING   3               ; select register bank 3
PUSH    AR2             ; push R2 in bank 3 (address 1Ah)
PUSH    AR7             ; push R7 in bank 3 (address 1Fh)

POP     AR7
POP     AR2

;-----------------------
POP     PSW             ; restore saved register bank
;=======================================================
;以下也是可行的
MOV     0Ah,#12H        ;间接方式 R2 bank 1
MOV     0FH,#34H        ;间接方式 R7 bank 1

PUSH    0Ah
PUSH    0FH

POP     0FH
POP     0Ah

AJMP $

END

#5

zaixuexi2012-02-09 23:52

膜拜楼上大牛