Re: Starting with No Byte Access

I have redefined C@ and C! to use @ and ! (below). Now to track down the
assembly instructions that do byte accesses ( B. ). The optimizer uses many
of them, so it needs to be turned off, but it is not readily apparent how to
turn off optimizing for the kernel too... commenting out include opt.f
altogether.

: C@ ( addr -- c ) \ Use @ to get c from addr, Big
Endian
  DUP [ %11 INVERT ] LITERAL AND \ get c's cell-aligned address
  @ ( a x0 ) \ fetch c's cell
  SWAP %11 AND ( x0 n ) \ get c's byte offset
  NEGATE 3 LSHIFT #24 + ( x0 y ) \ get c's source LSBit number (y =
-8x + 24, x is addr[1..0]); 3 LSHIFT is 8 * (multiply isn't defined)
  RSHIFT ( x0' ) \ shift c into LSByte
  $FF AND ( c ) \ strip x[31..8]
;

: C! ( c addr -- ) \ Use @ and ! to put c at addr, Big
Endian
  SWAP $FF AND SWAP \ strip c[31..8]
  DUP [ %11 INVERT ] LITERAL AND ( a0 ) \ get c's cell-aligned address
  DUP @ ( c' a a0 x0 ) \ fetch cell data at c's destination
  2SWAP %11 AND ( a0 x0 c' n ) \ get c's byte offset
  NEGATE 3 LSHIFT #24 + ( a0 x0 c' y ) \ get c's destination LSBit number
(y = -8x + 24, x is addr[1..0]); 3 LSHIFT is 8 * (multiply isn't defined)
  TUCK LSHIFT ( a0 x0 y x1 ) \ shift c into the byte position of
the cell-aligned address
  -ROT $FF ( a0 x1 x0 y m )
  SWAP LSHIFT INVERT AND ( a0 x1 x0' ) \ clear c's byte in destination cell
data
  OR SWAP ! \ store c's cell
;
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Received on Thu Dec 16 2004 - 08:35:37 PST