From: taviso@nospicedham.gmail.com   
      
   [I've rearranged your code to intermix code with assembly]   
      
   On 2023-06-24, Paul Edwards wrote:   
   > void dumplong(unsigned long x)   
   > _dumplong:   
   > 	push	bp   
   > 	mov	bp,sp   
      
   Note: Making space for locals, not an offset.   
      
   >     char buf[9];   
   > 	sub	sp,OFFSET L04604   
      
   Note: Loading far pointer to "0123..." into z   
      
   >     char *z = "0123456789abcdef";   
   > 	mov	ax,OFFSET L03767   
   > 	mov	dx,ds   
   > 	mov	WORD PTR -16[bp],ax   
   > 	mov	WORD PTR -14[bp],dx   
      
   >     y = 0;   
   > 	mov	WORD PTR ?y@?1??dumplong@@9@9,OFFSET 0   
      
   >     buf[0] = 'P';   
   >     buf[1] = 'P';   
   >     buf[2] = 'P';   
   >     buf[3] = 'P';   
   > 	mov	BYTE PTR -12[bp],OFFSET 80   
   > 	mov	BYTE PTR -11[bp],OFFSET 80   
   > 	mov	BYTE PTR -10[bp],OFFSET 80   
   > 	mov	BYTE PTR -9[bp],OFFSET 80   
      
   >     buf[3-y] = 'R';   
   > 	mov	ax,OFFSET 3   
   > 	sub	ax,WORD PTR ?y@?1??dumplong@@9@9   
   > 	lea	bx,WORD PTR -12[bp]   
   > 	add	bx,ax   
   > 	mov	BYTE PTR ss:[bx],OFFSET 82   
      
   >     buf[4] = 'P';   
   > 	mov	BYTE PTR -8[bp],OFFSET 80   
      
   >     buf[4+y] = 'S';   
   > 	mov	ax,WORD PTR ?y@?1??dumplong@@9@9   
   > 	add	ax,OFFSET 4   
   > 	lea	bx,WORD PTR -12[bp]   
   > 	add	bx,ax   
   > 	mov	BYTE PTR ss:[bx],OFFSET 83   
      
   >     buf[5] = 'P';   
   >     buf[6] = 'P';   
   >     buf[7] = 'P';   
   > 	mov	BYTE PTR -7[bp],OFFSET 80   
   > 	mov	BYTE PTR -6[bp],OFFSET 80   
   > 	mov	BYTE PTR -5[bp],OFFSET 80   
   >   
   >   
   > I've been looking at this for hours.   
   >   
   > Unless I've somehow stuffed up the test, this data is   
   > all being set to 'P'.   
      
   I don't follow, you set buf[3] to 'R' (shows as OFFSET 82 in the   
   disassembly) and buf[4] to 'S'.   
      
   >   
   > Regardless of whether I do a subtraction or an addition   
   > (of 0), the data is not changed.   
      
   You don't really explain what problem you're seeing, here is a   
   line-by-line:   
      
   >     buf[3-y] = 'R';   
      
   > 	mov	ax,OFFSET 3                             ; ax  = 3   
   > 	sub	ax,WORD PTR ?y@?1??dumplong@@9@9        ; ax -= y   
      
   So now ax is 3-y   
      
   > 	lea	bx,WORD PTR -12[bp]                     ; bx = &buf[0]   
   > 	add	bx,ax                                   ; bx += ax   
      
   So now bx is &buf[3-y]   
      
   > 	mov	BYTE PTR ss:[bx],OFFSET 82              ; *bx = 'R'   
      
   Set *bx = 'R', isn't that correct?   
      
   Tavis.   
      
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