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Message 116,275 of 117,927

Stephen Pelc to dxf

Re: Forth systems where do/?do pushes th

06 Mar 24 19:52:30

   From: stephen@vfxforth.com   
      
   On 6 Mar 2024 at 00:42:41 CET, "dxf"  wrote:   
      
   > On 5/03/2024 10:18 pm, Stephen Pelc wrote:   
   >> On 4 Mar 2024 at 18:24:09 CET, "Anton Ertl"  wrote:   
   >>>   
   >>> My question is: Which Forth systems have a DO/?DO that pushes the   
   >>> address that LOOP/+LOOP then jumps to?   
   >>>   
   >>> - anton   
   >>   
   >> VFX since the beginning.   
   >   
   > AFAICS the loop jump addr is hard-coded (JNO) as that was generally   
   > seen as most efficient:   
   >   
   > : test 10 0 do loop ;  ok   
   > see test   
   > TEST   
   > ( 005945D0    488D6DF0 )              LEA     RBP, [RBP+-10]   
   > ( 005945D4    48C745000A000000 )      MOV     QWord [RBP], # 0000000A   
   > ( 005945DC    48895D08 )              MOV     [RBP+08], RBX   
   > ( 005945E0    BB00000000 )            MOV     EBX, # 00000000   
   > ( 005945E5    E86615E9FFFF45590000000 CALL    00425B50  (DO) 00000000005945FF   
   > ( 005945F2    49FFC6 )                INC     R14   
   > ( 005945F5    49FFC7 )                INC     R15   
   > ( 005945F8    71F8 )                  JNO     005945F2   
   > ( 005945FA    415E )                  POP     R14   
   > ( 005945FC    415F )                  POP     R15   
   > ( 005945FE    58 )                    POP     RAX   
   > ( 005945FF    C3 )                    RET/NEXT   
   > ( 48 bytes, 12 instructions )   
      
   The three items pushed are   
     loop exit address   
     limit data of previous loop   
     index data of previous loop   
      
   The slightly odd list of items allows us to keep the index/limit data in   
   registers.   
      
   Stephen   
   --   
   Stephen Pelc, stephen@vfxforth.com   
   MicroProcessor Engineering, Ltd. - More Real, Less Time   
   133 Hill Lane, Southampton SO15 5AF, England   
   tel: +44 (0)78 0390 3612,  +34 649 662 974   
   http://www.mpeforth.com - free VFX Forth downloads   
      
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