管理参数和 return 地址时处理堆栈的正确约定

Question

当您需要访问参数 'below' 在堆？我使用的是 S12 Motorola/Freescale 处理器。（S12有：16位的D寄存器由A和B寄存器组成，每个寄存器有8位。X和Y索引寄存器各16位，一个程序计数器和一个堆栈指针）代码示例是：

MAIN ORG    00        ;Set the start of the program 
     LDD    #SomeValue   ;Load the D register with a value
     PSHD                ;Push D onto the stack
     JSR    ROUTINE      ;Go to the subroutine - pushes the PC to the SP
END_MAIN    END

ROUTINE     
     PULD                ;Pull the top of the stack into the D register
                         ;D now holds the address for returning to the 
                         ;main function. 
     PSHD                ;Push the return address back onto the stack
END_ROUTINE RTS          ;Return to Main routine

问题是栈顶保存着下一条指令的地址，这使得它很难移动。例如，如果我需要一个位于地址下方的参数，我将不得不手动调整 SP（这看起来很老套）或者我将不得不拉出堆栈的顶部并将其存储在一个寄存器中向上 space。最后一种方法的一个转折是将 return 地址存储在一个变量中，不幸的是，这里声明的变量是全局范围的，这感觉并不理想。

ReturnAddress EQU 00        ;Declare variable at address 00
STD           ReturnAddress    ;Store the D register's contents in variable

是否还有我在这里没有看到的其他选项？

Answer 1

感谢 Jester 的一些输入，观察堆栈中发生的事情并使用其中包含的参数是相当简单的。我写了一个简单的程序来演示按值和引用传递参数。

QUOTIENT    EQU     00       ;Variable to hold our QUOTIENT
REMAINDER   EQU     02       ;Variable to hold our REMAINDER

MAIN        ORG     00       ;Set the start of the program
            LDD     #!50        ;Load the D register with a value (16 bits)
            PSHD                ;Push D onto the stack (16 bits)
            LDD     #!10        ;Load the D register with a value (16 bits)
            PSHD                ;Push D onto the stack (16 bits)
            LDD     #QUOTIENT   ;Load the D register with an address (16 bits)
            PSHD                ;Push D onto the stack (16 bits)
            LDD     #REMAINDER  ;Load the D register with an address (16 bits)
            PSHD                ;Push D onto the stack (16 bits)
            JSR     DIVIDE      ;Push the PC onto the stack (16 bits).
            LEAS [=10=]A, SP         ;Instead of PULD 5x, thanks Jester
END_MAIN    END


;******************************************************************************;
;DIVIDE - This routine expects the following parameters to be on the stack:
; STACK
;( 0 ) - (16 bits for return address)
;( 2 ) - (16 bits of address to store the REMAINDER (ANSWER var reference))
;( 4 ) - (16 bits of address to store the QUOTIENT (ANSWER var reference))
;( 6 ) - (16 bits for divisor)
;( 8 ) - (16 bits for dividend)
;******************************************************************************;
DIVIDE      LDD     8,SP       ;Loads the dividend (50)
            LDX     6,SP       ;Loads the divisor (10)
            IDIV               ;Divide
            LDY     4,SP       ;Get the address of the Quotient
            STX     0,Y        ;Store at that address
            LDY     2,SP       ;Get the address of the remainder
            STD     0,Y        ;Store at that address
END_DIVIDE  RTS

管理参数和 return 地址时处理堆栈的正确约定

Proper convention for handling the stack when managing parameters and the return address

assembly

68hc12