1 # DCT "REMAP" scheduler
3 # Modifications made to create an in-place iterative DCT:
4 # Copyright (c) 2021 Luke Kenneth Casson Leighton <lkcl@lkcl.net>
8 # Original fastdctlee.py by Nayuki:
9 # Copyright (c) 2020 Project Nayuki. (MIT License)
10 # https://www.nayuki.io/page/fast-discrete-cosine-transform-algorithms
14 # bits of the integer 'val'.
15 def reverse_bits(val
, width
):
17 for _
in range(width
):
18 result
= (result
<< 1) |
(val
& 1)
23 # iterative version of [recursively-applied] half-rev.
24 # relies on the list lengths being power-of-two and the fact
25 # that bit-inversion of a list of binary numbers is the same
26 # as reversing the order of the list
27 # this version is dead easy to implement in hardware.
28 # a big surprise is that the half-reversal can be done with
29 # such a simple XOR. the inverse operation is slightly trickier
30 def halfrev2(vec
, pre_rev
=True):
32 for i
in range(len(vec
)):
34 res
.append(i ^
(i
>>1))
38 for ji
in range(1, bl
):
44 # python "yield" can be iterated. use this to make it clear how
45 # the indices are generated by using natural-looking nested loops
46 def iterate_dct_inner_halfswap_loadstore(SVSHAPE
):
47 # get indices to iterate over, in the required order
49 mode
= SVSHAPE
.lims
[1]
50 print ("inner halfswap loadstore", n
, mode
, SVSHAPE
.skip
)
52 # reference list for not needing to do data-swaps, just swap what
53 # *indices* are referenced (two levels of indirection at the moment)
54 # pre-reverse the data-swap list so that it *ends up* in the order 0123..
57 levels
= n
.bit_length() - 1
58 ji
= halfrev2(ji
, False)
59 if False: # swap: TODO, add extra bit-reverse mode
60 ri
= [reverse_bits(i
, levels
) for i
in range(n
)]
61 ji
= [ji
[ri
[i
]] for i
in range(n
)]
64 # invert order if requested
68 for i
, jl
in enumerate(ji
):
70 yield jl
, (0b111 if y_end
else 0b000)
73 # python "yield" can be iterated. use this to make it clear how
74 # the indices are generated by using natural-looking nested loops
75 def iterate_dct_inner_costable_indices(SVSHAPE
):
76 # get indices to iterate over, in the required order
78 mode
= SVSHAPE
.lims
[1]
79 print ("inner costable", mode
)
80 # creating lists of indices to iterate over in each dimension
81 # has to be done dynamically, because it depends on the size
82 # first, the size-based loop (which can be done statically)
88 # invert order if requested
98 # start an infinite (wrapping) loop
100 z_end
= 1 # doesn't exist in this, only 2 loops
103 for size
in x_r
: # loop over 3rd order dimension (size)
104 x_end
= size
== x_r
[-1]
105 # y_r schedule depends on size
108 for i
in range(0, n
, size
):
110 # invert if requested
111 if SVSHAPE
.invxyz
[1]: y_r
.reverse()
112 # two lists of half-range indices, e.g. j 0123, jr 7654
113 j
= list(range(0, halfsize
))
114 # invert if requested
115 if SVSHAPE
.invxyz
[2]: j_r
.reverse()
116 #print ("xform jr", jr)
117 # loop over 1st order dimension
118 for ci
, jl
in enumerate(j
):
120 # now depending on MODE return the index. inner butterfly
121 if SVSHAPE
.skip
== 0b00: # in [0b00, 0b10]:
122 result
= k
# offset into COS table
123 elif SVSHAPE
.skip
== 0b10: #
124 result
= ci
# coefficient helper
125 elif SVSHAPE
.skip
== 0b11: #
126 result
= size
# coefficient helper
128 ((y_end
and z_end
)<<1) |
129 ((y_end
and x_end
and z_end
)<<2))
131 yield result
+ SVSHAPE
.offset
, loopends
134 # python "yield" can be iterated. use this to make it clear how
135 # the indices are generated by using natural-looking nested loops
136 def iterate_dct_inner_butterfly_indices(SVSHAPE
):
137 # get indices to iterate over, in the required order
139 mode
= SVSHAPE
.lims
[1]
140 #print ("inner butterfly", mode, SVSHAPE.skip)
141 # creating lists of indices to iterate over in each dimension
142 # has to be done dynamically, because it depends on the size
143 # first, the size-based loop (which can be done statically)
149 # invert order if requested
150 if SVSHAPE
.invxyz
[0]:
156 # reference (read/write) the in-place data in *reverse-bit-order*
158 if SVSHAPE
.submode2
== 0b01:
159 levels
= n
.bit_length() - 1
160 ri
= [ri
[reverse_bits(i
, levels
)] for i
in range(n
)]
162 # reference list for not needing to do data-swaps, just swap what
163 # *indices* are referenced (two levels of indirection at the moment)
164 # pre-reverse the data-swap list so that it *ends up* in the order 0123..
167 if inplace_mode
and SVSHAPE
.submode2
== 0b01:
168 #print ("inplace mode")
169 ji
= halfrev2(ji
, True)
174 # start an infinite (wrapping) loop
178 for size
in x_r
: # loop over 3rd order dimension (size)
179 x_end
= size
== x_r
[-1]
180 # y_r schedule depends on size
183 for i
in range(0, n
, size
):
185 # invert if requested
186 if SVSHAPE
.invxyz
[1]: y_r
.reverse()
187 for i
in y_r
: # loop over 2nd order dimension
189 # two lists of half-range indices, e.g. j 0123, jr 7654
190 j
= list(range(i
, i
+ halfsize
))
191 jr
= list(range(i
+halfsize
, i
+ size
))
193 # invert if requested
194 if SVSHAPE
.invxyz
[2]: j_r
.reverse()
195 hz2
= halfsize
// 2 # zero stops reversing 1-item lists
196 #print ("xform jr", jr)
197 # loop over 1st order dimension
199 for ci
, (jl
, jh
) in enumerate(zip(j
, jr
)):
201 # now depending on MODE return the index. inner butterfly
202 if SVSHAPE
.skip
== 0b00: # in [0b00, 0b10]:
203 result
= ri
[ji
[jl
]] # lower half
204 elif SVSHAPE
.skip
== 0b01: # in [0b01, 0b11]:
205 result
= ri
[ji
[jh
]] # upper half
207 # COS table pre-generated mode
208 if SVSHAPE
.skip
== 0b10: #
209 result
= k
# cos table offset
211 # COS table generated on-demand ("Vertical-First") mode
212 if SVSHAPE
.skip
== 0b10: #
213 result
= ci
# coefficient helper
214 elif SVSHAPE
.skip
== 0b11: #
215 result
= size
# coefficient helper
217 ((y_end
and z_end
)<<1) |
218 ((y_end
and x_end
and z_end
)<<2))
220 yield result
+ SVSHAPE
.offset
, loopends
225 for ci
, (jl
, jh
) in enumerate(zip(j
[:hz2
], jr
[:hz2
])):
227 #print ("inplace swap", jh, jlh)
228 tmp1
, tmp2
= ji
[jlh
], ji
[jh
]
229 ji
[jlh
], ji
[jh
] = tmp2
, tmp1
231 # new k_start point for cos tables( runs inside x_r loop NOT i loop)
235 # python "yield" can be iterated. use this to make it clear how
236 # the indices are generated by using natural-looking nested loops
237 def iterate_dct_outer_butterfly_indices(SVSHAPE
):
238 # get indices to iterate over, in the required order
240 mode
= SVSHAPE
.lims
[1]
241 # creating lists of indices to iterate over in each dimension
242 # has to be done dynamically, because it depends on the size
243 # first, the size-based loop (which can be done statically)
249 # invert order if requested
250 if SVSHAPE
.invxyz
[0]:
256 #print ("outer butterfly")
258 # I-DCT, reference (read/write) the in-place data in *reverse-bit-order*
260 if SVSHAPE
.submode2
== 0b11:
261 levels
= n
.bit_length() - 1
262 ri
= [ri
[reverse_bits(i
, levels
)] for i
in range(n
)]
264 # reference list for not needing to do data-swaps, just swap what
265 # *indices* are referenced (two levels of indirection at the moment)
266 # pre-reverse the data-swap list so that it *ends up* in the order 0123..
268 inplace_mode
= False # need the space... SVSHAPE.skip in [0b10, 0b11]
269 if SVSHAPE
.submode2
== 0b11:
270 ji
= halfrev2(ji
, False)
275 # start an infinite (wrapping) loop
279 for size
in x_r
: # loop over 3rd order dimension (size)
281 x_end
= size
== x_r
[-1]
282 y_r
= list(range(0, halfsize
))
283 print ("itersum", halfsize
, size
, y_r
, "invert", SVSHAPE
.invxyz
[1])
284 # invert if requested
285 if SVSHAPE
.invxyz
[1]: y_r
.reverse()
286 for i
in y_r
: # loop over 2nd order dimension
288 # one list to create iterative-sum schedule
289 jr
= list(range(i
+halfsize
, i
+n
-halfsize
, size
))
290 # invert if requested
291 if SVSHAPE
.invxyz
[2]: jr
.reverse()
292 print ("itersum jr", i
+halfsize
, i
+size
, jr
,
293 "invert", SVSHAPE
.invxyz
[2])
294 hz2
= halfsize
// 2 # zero stops reversing 1-item lists
296 for ci
, jh
in enumerate(jr
): # loop over 1st order dimension
298 #print (" itersum", size, i, jh, jh+size)
300 # COS table pre-generated mode
301 if SVSHAPE
.skip
== 0b00: # in [0b00, 0b10]:
302 result
= ri
[ji
[jh
]] # lower half
303 elif SVSHAPE
.skip
== 0b01: # in [0b01, 0b11]:
304 result
= ri
[ji
[jh
+size
]] # upper half
305 elif SVSHAPE
.skip
== 0b10: #
306 result
= k
# cos table offset
308 # COS table generated on-demand ("Vertical-First") mode
309 if SVSHAPE
.skip
== 0b00: # in [0b00, 0b10]:
310 result
= ri
[ji
[jh
]] # lower half
311 elif SVSHAPE
.skip
== 0b01: # in [0b01, 0b11]:
312 result
= ri
[ji
[jh
+size
]] # upper half
313 elif SVSHAPE
.skip
== 0b10: #
314 result
= ci
# coefficient helper
315 elif SVSHAPE
.skip
== 0b11: #
316 result
= size
# coefficient helper
318 ((y_end
and z_end
)<<1) |
319 ((y_end
and x_end
and z_end
)<<2))
321 yield result
+ SVSHAPE
.offset
, loopends
324 # now in-place swap (disabled)
325 if False and SVSHAPE
.submode2
== 0b11:
326 j
= list(range(i
, i
+ halfsize
))
327 jr
= list(range(i
+halfsize
, i
+ size
))
329 for ci
, (jl
, jh
) in enumerate(zip(j
[:hz2
], jr
[:hz2
])):
331 tmp1
, tmp2
= ji
[jlh
], ji
[jh
]
332 print ("inplace swap", jh
, jlh
, "actual", tmp1
, tmp2
)
333 ji
[jlh
], ji
[jh
] = tmp2
, tmp1
335 # new k_start point for cos tables( runs inside x_r loop NOT i loop)
339 def pprint_schedule(schedule
, n
):
344 tablestep
= n
// size
345 print ("size %d halfsize %d tablestep %d" % \
346 (size
, halfsize
, tablestep
))
347 for i
in range(0, n
, size
):
348 prefix
= "i %d\t" % i
349 for j
in range(i
, i
+ halfsize
):
350 (jl
, je
), (jh
, he
) = schedule
[idx
]
351 print (" %-3d\t%s j=%-2d jh=%-2d "
352 "j[jl=%-2d] j[jh=%-2d]" % \
353 (idx
, prefix
, j
, j
+halfsize
,
356 "end", bin(je
)[2:], bin(je
)[2:])
360 def pprint_schedule_outer(schedule
, n
):
365 tablestep
= n
// size
366 print ("size %d halfsize %d tablestep %d" % \
367 (size
, halfsize
, tablestep
))
368 y_r
= list(range(0, halfsize
))
370 prefix
= "i %d\t" % i
371 jr
= list(range(i
+halfsize
, i
+n
-halfsize
, size
))
373 (jl
, je
), (jh
, he
) = schedule
[idx
]
374 print (" %-3d\t%s j=%-2d jh=%-2d "
375 "j[jl=%-2d] j[jh=%-2d]" % \
376 (idx
, prefix
, j
, j
+halfsize
,
379 "end", bin(je
)[2:], bin(je
)[2:])
384 # totally cool *in-place* DCT algorithm using yield REMAPs
390 print ("transform2", n
)
391 levels
= n
.bit_length() - 1
396 # reference (read/write) the in-place data in *reverse-bit-order*
398 ri
= [ri
[reverse_bits(i
, levels
)] for i
in range(n
)]
400 # and pretend we LDed data in half-swapped *and* bit-reversed order as well
401 # TODO: merge these two
402 vec
= halfrev2(vec
, False)
403 vec
= [vec
[ri
[i
]] for i
in range(n
)]
405 # create a cos table: not strictly necessary but here for illustrative
406 # purposes, to demonstrate the point that it really *is* iterative.
407 # this table could be cached and used multiple times rather than
408 # computed every time.
413 for ci
in range(halfsize
):
414 coeff
= (math
.cos((ci
+ 0.5) * math
.pi
/ size
) * 2.0)
416 print ("coeff", size
, "ci", ci
, "k", len(ctable
)-1,
417 "i/n", (ci
+0.5)/size
, coeff
)
425 SVSHAPE0
.lims
= [xdim
, 4, 0]
427 SVSHAPE0
.submode2
= 0b01
429 SVSHAPE0
.offset
= 0 # experiment with different offset, here
430 SVSHAPE0
.invxyz
= [1,0,0] # inversion if desired
433 SVSHAPE1
.lims
= [xdim
, 4, 0]
435 SVSHAPE1
.submode2
= 0b01
437 SVSHAPE1
.offset
= 0 # experiment with different offset, here
438 SVSHAPE1
.invxyz
= [1,0,0] # inversion if desired
441 SVSHAPE2
.lims
= [xdim
, 4, 0]
443 SVSHAPE2
.submode2
= 0b01
445 SVSHAPE2
.offset
= 0 # experiment with different offset, here
446 SVSHAPE2
.invxyz
= [1,0,0] # inversion if desired
448 # enumerate over the iterator function, getting new indices
449 i0
= iterate_dct_inner_costable_indices(SVSHAPE0
)
450 i1
= iterate_dct_inner_costable_indices(SVSHAPE1
)
451 i2
= iterate_dct_inner_costable_indices(SVSHAPE2
)
452 for ((ci
, cie
), (size
, sze
), (k
, ke
)) in \
454 print ("xform2 cos", ci
, size
, k
)
455 coeff
= (math
.cos((ci
+ 0.5) * math
.pi
/ size
) * 2.0)
456 assert coeff
== ctable
[k
]
457 print ("coeff", size
, "ci", ci
, "k", k
,
458 "i/n", (ci
+0.5)/size
, coeff
,
459 "end", bin(cie
), bin(sze
), bin(ke
))
460 if cie
== 0b111: # all loops end
469 SVSHAPE0
.lims
= [xdim
, 0b000001, 0]
471 SVSHAPE0
.submode2
= 0b01
473 SVSHAPE0
.offset
= 0 # experiment with different offset, here
474 SVSHAPE0
.invxyz
= [1,0,0] # inversion if desired
475 # j+halfstep schedule
477 SVSHAPE1
.lims
= [xdim
, 0b000001, 0]
479 SVSHAPE1
.submode2
= 0b01
481 SVSHAPE1
.offset
= 0 # experiment with different offset, here
482 SVSHAPE1
.invxyz
= [1,0,0] # inversion if desired
485 SVSHAPE2
.lims
= [xdim
, 0b000001, 0]
487 SVSHAPE2
.submode2
= 0b01
489 SVSHAPE2
.offset
= 0 # experiment with different offset, here
490 SVSHAPE2
.invxyz
= [1,0,0] # inversion if desired
493 SVSHAPE3
.lims
= [xdim
, 0b000001, 0]
495 SVSHAPE3
.submode2
= 0b01
497 SVSHAPE3
.offset
= 0 # experiment with different offset, here
498 SVSHAPE3
.invxyz
= [1,0,0] # inversion if desired
500 # enumerate over the iterator function, getting new indices
501 i0
= iterate_dct_inner_butterfly_indices(SVSHAPE0
)
502 i1
= iterate_dct_inner_butterfly_indices(SVSHAPE1
)
503 i2
= iterate_dct_inner_butterfly_indices(SVSHAPE2
)
504 i3
= iterate_dct_inner_butterfly_indices(SVSHAPE3
)
505 for k
, ((jl
, jle
), (jh
, jhe
), (ci
, cie
), (size
, sze
)) in \
506 enumerate(zip(i0
, i1
, i2
, i3
)):
507 t1
, t2
= vec
[jl
], vec
[jh
]
508 print ("xform2", jl
, jh
, ci
, size
)
509 coeff
= (math
.cos((ci
+ 0.5) * math
.pi
/ size
) * 2.0)
510 #assert coeff == ctable[k]
512 vec
[jh
] = (t1
- t2
) * (1/coeff
)
513 print ("coeff", size
, "ci", ci
,
515 "i/n", (ci
+0.5)/size
, coeff
, vec
[jl
],
517 "end", bin(jle
), bin(jhe
))
518 if jle
== 0b111: # all loops end
521 print("transform2 pre-itersum", vec
)
523 # now things are in the right order for the outer butterfly.
527 SVSHAPE0
.lims
= [xdim
, 0b0000010, 0]
528 SVSHAPE0
.submode2
= 0b100
531 SVSHAPE0
.offset
= 0 # experiment with different offset, here
532 SVSHAPE0
.invxyz
= [0,0,0] # inversion if desired
533 # j+halfstep schedule
535 SVSHAPE1
.lims
= [xdim
, 0b0000010, 0]
537 SVSHAPE1
.submode2
= 0b100
539 SVSHAPE1
.offset
= 0 # experiment with different offset, here
540 SVSHAPE1
.invxyz
= [0,0,0] # inversion if desired
542 # enumerate over the iterator function, getting new indices
543 i0
= iterate_dct_outer_butterfly_indices(SVSHAPE0
)
544 i1
= iterate_dct_outer_butterfly_indices(SVSHAPE1
)
545 for k
, ((jl
, jle
), (jh
, jhe
)) in enumerate(zip(i0
, i1
)):
546 print ("itersum jr", jl
, jh
,
547 "end", bin(jle
), bin(jhe
))
550 if jle
== 0b111: # all loops end
553 print("transform2 result", vec
)
559 # set the dimension sizes here
562 ydim
= 0 # not needed
563 zdim
= 0 # again, not needed
575 SVSHAPE0
.lims
= [xdim
, 0b0000010, 0]
576 SVSHAPE0
.submode2
= 0b100
579 SVSHAPE0
.offset
= 0 # experiment with different offset, here
580 SVSHAPE0
.invxyz
= [1,0,1] # inversion if desired
581 # j+halfstep schedule
583 SVSHAPE1
.lims
= [xdim
, 0b0000010, 0]
585 SVSHAPE1
.submode2
= 0b100
587 SVSHAPE1
.offset
= 0 # experiment with different offset, here
588 SVSHAPE1
.invxyz
= [1,0,1] # inversion if desired
590 # enumerate over the iterator function, getting new indices
592 i0
= iterate_dct_outer_butterfly_indices(SVSHAPE0
)
593 i1
= iterate_dct_outer_butterfly_indices(SVSHAPE1
)
594 for idx
, (jl
, jh
) in enumerate(zip(i0
, i1
)):
595 schedule
.append((jl
, jh
))
596 if jl
[1] == 0b111: # end
599 # ok now pretty-print the results, with some debug output
600 print ("outer i-dct butterfly")
601 pprint_schedule_outer(schedule
, n
)
609 SVSHAPE0
.lims
= [xdim
, 0b000001, 0]
611 SVSHAPE0
.submode2
= 0b11
613 SVSHAPE0
.offset
= 0 # experiment with different offset, here
614 SVSHAPE0
.invxyz
= [0,0,0] # inversion if desired
615 # j+halfstep schedule
617 SVSHAPE1
.lims
= [xdim
, 0b000001, 0]
619 SVSHAPE1
.submode2
= 0b11
621 SVSHAPE1
.offset
= 0 # experiment with different offset, here
622 SVSHAPE1
.invxyz
= [0,0,0] # inversion if desired
624 # enumerate over the iterator function, getting new indices
626 i0
= iterate_dct_inner_butterfly_indices(SVSHAPE0
)
627 i1
= iterate_dct_inner_butterfly_indices(SVSHAPE1
)
628 for idx
, (jl
, jh
) in enumerate(zip(i0
, i1
)):
629 schedule
.append((jl
, jh
))
630 if jl
[1] == 0b111: # end
633 # ok now pretty-print the results, with some debug output
634 print ("inner butterfly")
635 pprint_schedule(schedule
, n
)
640 # for DCT half-swap LDs
643 SVSHAPE0
.lims
= [xdim
, 0b000101, zdim
]
645 SVSHAPE0
.submode2
= 0b01
647 SVSHAPE0
.offset
= 0 # experiment with different offset, here
648 SVSHAPE0
.invxyz
= [0,0,0] # inversion if desired
651 levels
= n
.bit_length() - 1
653 ri
= [reverse_bits(i
, levels
) for i
in range(n
)]
654 av
= halfrev2(avi
, False)
655 av
= [av
[ri
[i
]] for i
in range(n
)]
657 i0
= iterate_dct_inner_halfswap_loadstore(SVSHAPE0
)
658 for idx
, (jl
) in enumerate(i0
):
659 print ("inverse half-swap ld", idx
, jl
, av
[idx
])
660 if jl
[1] == 0b111: # end
665 # set the dimension sizes here
668 ydim
= 0 # not needed
669 zdim
= 0 # again, not needed
681 SVSHAPE0
.lims
= [xdim
, 0b000001, zdim
]
682 SVSHAPE0
.submode2
= 0b010
685 SVSHAPE0
.offset
= 0 # experiment with different offset, here
686 SVSHAPE0
.invxyz
= [0,0,0] # inversion if desired
687 # j+halfstep schedule
689 SVSHAPE1
.lims
= [xdim
, 0b000001, zdim
]
690 SVSHAPE1
.submode2
= 0b010
693 SVSHAPE1
.offset
= 0 # experiment with different offset, here
694 SVSHAPE1
.invxyz
= [0,0,0] # inversion if desired
696 # enumerate over the iterator function, getting new indices
698 i0
= iterate_dct_inner_butterfly_indices(SVSHAPE0
)
699 i1
= iterate_dct_inner_butterfly_indices(SVSHAPE1
)
700 for idx
, (jl
, jh
) in enumerate(zip(i0
, i1
)):
701 schedule
.append((jl
, jh
))
702 if jl
[1] == 0b111: # end
705 # ok now pretty-print the results, with some debug output
706 print ("inner butterfly")
707 pprint_schedule(schedule
, n
)
716 SVSHAPE0
.lims
= [xdim
, 0b000010, zdim
]
718 SVSHAPE0
.submode2
= 0b100
720 SVSHAPE0
.offset
= 0 # experiment with different offset, here
721 SVSHAPE0
.invxyz
= [1,0,0] # inversion if desired
722 # j+halfstep schedule
724 SVSHAPE1
.lims
= [xdim
, 0b000010, zdim
]
726 SVSHAPE1
.submode2
= 0b100
728 SVSHAPE1
.offset
= 0 # experiment with different offset, here
729 SVSHAPE1
.invxyz
= [1,0,0] # inversion if desired
731 # enumerate over the iterator function, getting new indices
733 i0
= iterate_dct_outer_butterfly_indices(SVSHAPE0
)
734 i1
= iterate_dct_outer_butterfly_indices(SVSHAPE1
)
735 for idx
, (jl
, jh
) in enumerate(zip(i0
, i1
)):
736 schedule
.append((jl
, jh
))
737 if jl
[1] == 0b111: # end
740 # ok now pretty-print the results, with some debug output
741 print ("outer butterfly")
742 pprint_schedule_outer(schedule
, n
)
744 # for DCT half-swap LDs
747 SVSHAPE0
.lims
= [xdim
, 0b000101, zdim
]
749 SVSHAPE0
.submode2
= 0
751 SVSHAPE0
.offset
= 0 # experiment with different offset, here
752 SVSHAPE0
.invxyz
= [0,0,0] # inversion if desired
755 levels
= n
.bit_length() - 1
757 ri
= [reverse_bits(i
, levels
) for i
in range(n
)]
758 av
= halfrev2(avi
, False)
759 av
= [av
[ri
[i
]] for i
in range(n
)]
762 i0
= iterate_dct_inner_halfswap_loadstore(SVSHAPE0
)
763 for idx
, (jl
) in enumerate(i0
):
764 print ("inverse half-swap ld", idx
, jl
, av
[idx
])
765 if jl
[1] == 0b111: # end
770 if __name__
== '__main__':