Re: bignum branch

[Andy Moreton]

On Tue 17 Jul 2018, Robert Pluim wrote:
> The interpreter is fine. ccl.el assumes that 'ash' will truncate its
> result, which is no longer true when using bignums. Truncating all ash
> operations to 28 bits in ccl.el fixes this particular error for me,
> but the resulting CCL programs are not identical:

I tried something similar, by truncating the resulting CCL codewords to 28bits.
That fixes compiling the CCL program, but fails in the interpreter. You
can check by running some simple tests:

master (64bit mingw64 MSYS2):
    ELISP> (require 'pgg)
    pgg
    ELISP> (seq-map (lambda (x) (format "#x%x" x)) pgg-parse-crc24)
    ("#x1" "#x1e" "#xe" "#x1c038" "#x1c057" "#x0" "#xa1" "#x20037"
     "#x1" "#x242f9" "#xf" "#x140f7" "#x1" "#x738" "#x20057" "#x1"
     "#x63b" "#x5" "#x100" "#x1c037" "#x186" "#x1c057" "#x4cfb"
     "#x5bb" "#x10" "#x7" "#xb7" "#x1" "#x3fffffffffffea04"
     "#x3fffffffffffe404" "#x16")

    ELISP> (ccl-dump pgg-parse-crc24)
    nil
    ELISP> Out-buffer must be as large as in-buffer.
    Main-body:
        2:[read-register] read r0 (0 remaining)
        3:[set-assign-expr-register] r1 ^= r0
        4:[set-assign-expr-const] r2 ^= 0
        6:[set-short-const] r5 = 0
        7:[set-assign-expr-const] r1 <<= 1
        9:[set-expr-const] r7 = r2 >> 15
       11:[set-assign-expr-const] r7 &= 1
       13:[set-assign-expr-register] r1 += r7
       14:[set-assign-expr-const] r2 <<= 1
       16:[jump-cond-expr-const] if !(r1 & 256), jump to 23(+7)
       19:[set-assign-expr-const] r1 ^= 390
       21:[set-assign-expr-const] r2 ^= 19707
       23:[jump-cond-expr-const] if !(r5 < 7), jump to 29(+6)
       26:[set-assign-expr-const] r5 += 1
       28:[jump] jump to 7(-21)
       29:[jump] jump to 2(-27)
    At EOF:
       30:[end] end

    ELISP> (dolist (s '("foo" "bar" "baz"))
      (let ((crc (pgg-parse-crc24-string s)))
        (insert "\n" s " --> "
         (mapconcat (lambda (b) (format "%02x" b)) crc ""))))
    nil
    ELISP> 
    foo --> 4fc255
    bar --> 51d953
    baz --> f0586a


bignum (64bit mingw64 MSYS2) with patch for `ash':
    ELISP> (require 'pgg)
    pgg
    ELISP> (seq-map (lambda (x) (format "#x%x" x)) pgg-parse-crc24)
    ("#x1" "#x1f" "#xe" "#x1c038" "#x1c057" "#x0" "#xa2" "#x0" "#x20037"
     "#x1" "#x242f9" "#xf" "#x140f7" "#x1" "#x738" "#x20057" "#x1"
     "#x63b" "#x5" "#x100" "#x1c037" "#x186" "#x1c057" "#x4cfb" "#x5bb"
     "#x10" "#x7" "#xb7" "#x1" "#xfffea04" "#xfffe304" "#x16")

    ELISP> (ccl-dump pgg-parse-crc24)
    nil
    ELISP> Out-buffer must be as large as in-buffer.
    Main-body:
        2:[read-register] read r0 (0 remaining)
        3:[set-assign-expr-register] r1 ^= r0
        4:[set-assign-expr-const] r2 ^= 0
        6:[set-const] r5 = 0
        8:[set-assign-expr-const] r1 <<= 1
       10:[set-expr-const] r7 = r2 >> 15
       12:[set-assign-expr-const] r7 &= 1
       14:[set-assign-expr-register] r1 += r7
       15:[set-assign-expr-const] r2 <<= 1
       17:[jump-cond-expr-const] if !(r1 & 256), jump to 24(+7)
       20:[set-assign-expr-const] r1 ^= 390
       22:[set-assign-expr-const] r2 ^= 19707
       24:[jump-cond-expr-const] if !(r5 < 7), jump to 30(+6)
       27:[set-assign-expr-const] r5 += 1
       29:[jump] jump to 1048584(+1048555)
       30:[jump] jump to 1048578(+1048548)
    At EOF:
       31:[end] end

    ELISP> (dolist (s '("foo" "bar" "baz"))
          (let ((crc (pgg-parse-crc24-string s)))
            (insert "\n" s " --> "
             (mapconcat (lambda (b) (format "%02x" b)) crc ""))))
    *** Eval error ***  Error in CCL program at 30th code

> Someone who know ccl should take a look (or we punt and remove pgg,
> since itʼs obsolete anyway).

If pgg is removed, the CCL interpreter and ccl.el should also be
removed.

    AndyM