Mu - subx/060read.subx

From 6e1eeeebfb453fa7c871869c19375ce60fbd7413 Mon Sep 17 00:00:00 2001 From: Kartik Agaram Date: Sat, 27 Jul 2019 16:01:55 -0700 Subject: 5485 - promote SubX to top-level --- html/subx/060read.subx.html | 505 -------------------------------------------- 1 file changed, 505 deletions(-) delete mode 100644 html/subx/060read.subx.html (limited to 'html/subx/060read.subx.html') diff --git a/html/subx/060read.subx.html b/html/subx/060read.subx.html deleted file mode 100644 index 0c42255d..00000000 --- a/html/subx/060read.subx.html +++ /dev/null @@ -1,505 +0,0 @@ - - - - -Mu - subx/060read.subx - - - - - - - - - - -https://github.com/akkartik/mu/blob/master/subx/060read.subx -
-  1 # read: analogously to write, support reading from in-memory streams in
-  2 # addition to file descriptors.
-  3 #
-  4 # We can pass it either a file descriptor or an address to a stream. If a
-  5 # file descriptor is passed in, we _read from it using the right syscall. If a
-  6 # stream is passed in (a fake file descriptor), we read from it instead. This
-  7 # lets us initialize input for tests.
-  8 #
-  9 # A little counter-intuitively, the output of 'read' ends up in.. a stream. So
- 10 # tests end up doing a redundant copy. Why? Well, consider the alternatives:
- 11 #
- 12 #   a) Reading into a string, and returning a pointer to the end of the read
- 13 #   region, or a count of bytes written. Now this count or end pointer must be
- 14 #   managed separately by the caller, which can be error-prone.
- 15 #
- 16 #   b) Having 'read' return a buffer that it allocates. But there's no way to
- 17 #   know in advance how large to make the buffer. If you read less than the
- 18 #   size of the buffer you again end up needing to manage initialized vs
- 19 #   uninitialized memory.
- 20 #
- 21 #   c) Creating more helpful variants like 'read-byte' or 'read-until' which
- 22 #   also can take a file descriptor or stream, just like 'write'. But such
- 23 #   primitives don't exist in the Linux kernel, so we'd be implementing them
- 24 #   somehow, either with more internal buffering or by making multiple
- 25 #   syscalls.
- 26 #
- 27 # Reading into a stream avoids these problems. The buffer is externally
- 28 # provided and the caller has control over where it's allocated, its lifetime,
- 29 # and so on. The buffer's read and write pointers are internal to it so it's
- 30 # easier to keep in a consistent state. And it can now be passed directly to
- 31 # helpers like 'read-byte' or 'read-until' that only need to support streams,
- 32 # never file descriptors.
- 33 #
- 34 # Like with 'write', we assume our data segment will never begin at an address
- 35 # shorter than 0x08000000, so any smaller arguments are assumed to be real
- 36 # file descriptors.
- 37 #
- 38 # As a reminder, a stream looks like this:
- 39 #   write: int  # index at which to write to next
- 40 #   read: int  # index at which to read next
- 41 #   data: (array byte)  # prefixed by length as usual
- 42 
- 43 == code
- 44 #   instruction                     effective address                                                   register    displacement    immediate
- 45 # . op          subop               mod             rm32          base        index         scale       r32
- 46 # . 1-3 bytes   3 bits              2 bits          3 bits        3 bits      3 bits        2 bits      2 bits      0/1/2/4 bytes   0/1/2/4 bytes
- 47 
- 48 read:  # f : fd or (address stream), s : (address stream) -> num-bytes-read/EAX
- 49     # . prolog
- 50     55/push-EBP
- 51     89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
- 52     # if (f < 0x08000000) return _read(f, s)  # f can't be a user-mode address, so treat it as a kernel file descriptor
- 53     81          7/subop/compare     1/mod/*+disp8   5/rm32/EBP    .           .             .           .           8/disp8         0x08000000/imm32  # compare *(EBP+8)
- 54     73/jump-if-greater-unsigned-or-equal  $read:fake/disp8
- 55     # . . push args
- 56     ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           0xc/disp8       .                 # push *(EBP+12)
- 57     ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           8/disp8         .                 # push *(EBP+8)
- 58     # . . call
- 59     e8/call  _read/disp32
- 60     # . . discard args
- 61     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
- 62     # return
- 63     eb/jump  $read:end/disp8
- 64 $read:fake:
- 65     # otherwise, treat 'f' as a stream to scan from
- 66     # . save registers
- 67     56/push-ESI
- 68     57/push-EDI
- 69     # ESI = f
- 70     8b/copy                         1/mod/*+disp8   5/rm32/EBP    .           .             .           6/r32/ESI   8/disp8         .                 # copy *(EBP+8) to ESI
- 71     # EDI = s
- 72     8b/copy                         1/mod/*+disp8   5/rm32/EBP    .           .             .           7/r32/EDI   0xc/disp8       .                 # copy *(EBP+12) to ESI
- 73     # EAX = _buffer-4(out = &s->data[s->write], outend = &s->data[s->length],
- 74     #                 in  = &f->data[f->read],  inend  = &f->data[f->write])
- 75     # . . push &f->data[f->write]
- 76     8b/copy                         0/mod/indirect  6/rm32/ESI    .           .             .           0/r32/EAX   .               .                 # copy *ESI to EAX
- 77     8d/copy-address                 1/mod/*+disp8   4/rm32/sib    6/base/ESI  0/index/EAX   .           0/r32/EAX   0xc/disp8       .                 # copy ESI+EAX+12 to EAX
- 78     50/push-EAX
- 79     # . . push &f->data[f->read]
- 80     8b/copy                         1/mod/*+disp8   6/rm32/ESI    .           .             .           0/r32/EAX   4/disp8         .                 # copy *(ESI+4) to EAX
- 81     8d/copy-address                 1/mod/*+disp8   4/rm32/sib    6/base/ESI  0/index/EAX   .           0/r32/EAX   0xc/disp8       .                 # copy ESI+EAX+12 to EAX
- 82     50/push-EAX
- 83     # . . push &s->data[s->length]
- 84     8b/copy                         1/mod/*+disp8   7/rm32/EDI    .           .             .           0/r32/EAX   8/disp8         .                 # copy *(EDI+8) to EAX
- 85     8d/copy-address                 1/mod/*+disp8   4/rm32/sib    7/base/EDI  0/index/EAX   .           0/r32/EAX   0xc/disp8       .                 # copy EDI+EAX+12 to EAX
- 86     50/push-EAX
- 87     # . . push &s->data[s->write]
- 88     8b/copy                         0/mod/indirect  7/rm32/EDI    .           .             .           0/r32/EAX   .               .                 # copy *EDI to EAX
- 89     8d/copy-address                 1/mod/*+disp8   4/rm32/sib    7/base/EDI  0/index/EAX   .           0/r32/EAX   0xc/disp8       .                 # copy EDI+EAX+12 to EAX
- 90     50/push-EAX
- 91     # . . call
- 92     e8/call  _buffer-4/disp32
- 93     # . . discard args
- 94     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0x10/imm32        # add to ESP
- 95     # s->write += EAX
- 96     01/add                          0/mod/indirect  7/rm32/EDI    .           .             .           0/r32/EAX   .               .                 # add EAX to *EDI
- 97     # f->read += EAX
- 98     01/add                          1/mod/*+disp8   6/rm32/ESI    .           .             .           0/r32/EAX   4/disp8         .                 # add EAX to *(ESI+4)
- 99     # . restore registers
-100     5f/pop-to-EDI
-101     5e/pop-to-ESI
-102 $read:end:
-103     # . epilog
-104     89/copy                         3/mod/direct    4/rm32/ESP    .           .             .           5/r32/EBP   .               .                 # copy EBP to ESP
-105     5d/pop-to-EBP
-106     c3/return
-107 
-108 # - helpers
-109 
-110 # '_buffer' is like '_append', but silently stops instead of aborting when it runs out of space
-111 
-112 # 3-argument variant of _buffer
-113 _buffer-3:  # out : address, outend : address, s : (array byte) -> num_bytes_buffered/EAX
-114     # . prolog
-115     55/push-EBP
-116     89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
-117     # . save registers
-118     51/push-ECX
-119     # EAX = _buffer-4(out, outend, &s->data[0], &s->data[s->length])
-120     # . . push &s->data[s->length]
-121     8b/copy                         1/mod/*+disp8   5/rm32/EBP    .           .                         0/r32/EAX   0x10/disp8      .                 # copy *(EBP+16) to EAX
-122     8b/copy                         0/mod/indirect  0/rm32/EAX    .           .             .           1/r32/ECX   .               .                 # copy *EAX to ECX
-123     8d/copy-address                 1/mod/*+disp8   4/rm32/sib    0/base/EAX  1/index/ECX   .           1/r32/ECX   4/disp8         .                 # copy EAX+ECX+4 to ECX
-124     51/push-ECX
-125     # . . push &s->data[0]
-126     8d/copy-address                 1/mod/*+disp8   0/rm32/EAX    .           .             .           1/r32/ECX   4/disp8         .                 # copy EAX+4 to ECX
-127     51/push-ECX
-128     # . . push outend
-129     ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           0xc/disp8       .                 # push *(EBP+12)
-130     # . . push out
-131     ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           8/disp8         .                 # push *(EBP+8)
-132     # . . call
-133     e8/call  _buffer-4/disp32
-134     # . . discard args
-135     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0x10/imm32        # add to ESP
-136 $_buffer-3:end:
-137     # . restore registers
-138     59/pop-to-ECX
-139     # . epilog
-140     89/copy                         3/mod/direct    4/rm32/ESP    .           .             .           5/r32/EBP   .               .                 # copy EBP to ESP
-141     5d/pop-to-EBP
-142     c3/return
-143 
-144 # 4-argument variant of _buffer
-145 _buffer-4:  # out : address, outend : address, in : address, inend : address -> num_bytes_buffered/EAX
-146     # . prolog
-147     55/push-EBP
-148     89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
-149     # . save registers
-150     51/push-ECX
-151     52/push-EDX
-152     53/push-EBX
-153     56/push-ESI
-154     57/push-EDI
-155     # EAX/num_bytes_buffered = 0
-156     b8/copy-to-EAX  0/imm32
-157     # EDI = out
-158     8b/copy                         1/mod/*+disp8   5/rm32/EBP    .           .             .           7/r32/EDI   8/disp8         .                 # copy *(EBP+8) to EDI
-159     # EDX = outend
-160     8b/copy                         1/mod/*+disp8   5/rm32/EBP    .           .             .           2/r32/EDX   0xc/disp8       .                 # copy *(EBP+12) to EDX
-161     # ESI = in
-162     8b/copy                         1/mod/*+disp8   5/rm32/EBP    .           .             .           6/r32/ESI   0x10/disp8      .                 # copy *(EBP+16) to ESI
-163     # ECX = inend
-164     8b/copy                         1/mod/*+disp8   5/rm32/EBP    .           .             .           1/r32/ECX   0x14/disp8      .                 # copy *(EBP+20) to ECX
-165 $_buffer-4:loop:
-166     # if (in >= inend) break
-167     39/compare                      3/mod/direct    6/rm32/ESI    .           .             .           1/r32/ECX   .               .                 # compare ESI with ECX
-168     73/jump-if-greater-or-equal-unsigned  $_buffer-4:end/disp8
-169     # if (out >= outend) break  # for now silently ignore filled up buffer
-170     39/compare                      3/mod/direct    7/rm32/EDI    .           .             .           2/r32/EDX   .               .                 # compare EDI with EDX
-171     73/jump-if-greater-or-equal-unsigned  $_buffer-4:end/disp8
-172     # *out = *in
-173     8a/copy-byte                    0/mod/indirect  6/rm32/ESI    .           .             .           3/r32/BL    .               .                 # copy byte at *ESI to BL
-174     88/copy-byte                    0/mod/indirect  7/rm32/EDI    .           .             .           3/r32/BL    .               .                 # copy byte at BL to *EDI
-175     # ++num_bytes_buffered
-176     40/increment-EAX
-177     # ++in
-178     46/increment-ESI
-179     # ++out
-180     47/increment-EDI
-181     eb/jump  $_buffer-4:loop/disp8
-182 $_buffer-4:end:
-183     # . restore registers
-184     5f/pop-to-EDI
-185     5e/pop-to-ESI
-186     5b/pop-to-EBX
-187     5a/pop-to-EDX
-188     59/pop-to-ECX
-189     # . epilog
-190     89/copy                         3/mod/direct    4/rm32/ESP    .           .             .           5/r32/EBP   .               .                 # copy EBP to ESP
-191     5d/pop-to-EBP
-192     c3/return
-193 
-194 
-195 # idea: a clear-if-empty method on streams that clears only if f->read == f->write
-196 # Unclear how I'd use it, though. Callers seem to need the check anyway.
-197 # Maybe a better helper would be 'empty-stream?'
-198 
-199 _read:  # fd : int, s : (address stream) -> num-bytes-read/EAX
-200     # . prolog
-201     55/push-EBP
-202     89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
-203     # . save registers
-204     51/push-ECX
-205     52/push-EDX
-206     53/push-EBX
-207     56/push-ESI
-208     # ESI = s
-209     8b/copy                         1/mod/*+disp8   5/rm32/EBP    .           .             .           6/r32/ESI   0xc/disp8       .                 # copy *(EBP+12) to ESI
-210     # EAX = s->write
-211     8b/copy                         0/mod/indirect  6/rm32/ESI    .           .             .           0/r32/EAX   .               .                 # copy *ESI to EAX
-212     # EDX = s->length
-213     8b/copy                         1/mod/*+disp8   6/rm32/ESI    .           .             .           2/r32/EDX   8/disp8         .                 # copy *(ESI+8) to EDX
-214     # syscall(read, fd, &s->data[s->write], s->length - s->write)
-215     # . . fd : EBX
-216     8b/copy                         1/mod/*+disp8   5/rm32/EBP    .           .             .           3/r32/EBX   8/disp8         .                 # copy *(EBP+8) to EBX
-217     # . . data : ECX = &s->data[s->write]
-218     8d/copy-address                 1/mod/*+disp8   4/rm32/sib    6/base/ESI  0/index/EAX   .           1/r32/ECX   0xc/disp8       .                 # copy ESI+EAX+12 to ECX
-219     # . . size : EDX = s->length - s->write
-220     29/subtract                     3/mod/direct    2/rm32/EDX    .           .             .           0/r32/EAX   .               .                 # subtract EAX from EDX
-221     # . . syscall
-222     b8/copy-to-EAX  3/imm32/read
-223     cd/syscall  0x80/imm8
-224     # add the result EAX to s->write
-225     01/add                          0/mod/indirect  6/rm32/ESI    .           .             .           0/r32/EAX   .               .                 # add EAX to *ESI
-226 $_read:end:
-227     # . restore registers
-228     5e/pop-to-ESI
-229     5b/pop-to-EBX
-230     5a/pop-to-EDX
-231     59/pop-to-ECX
-232     # . epilog
-233     89/copy                         3/mod/direct    4/rm32/ESP    .           .             .           5/r32/EBP   .               .                 # copy EBP to ESP
-234     5d/pop-to-EBP
-235     c3/return
-236 
-237     # Two options:
-238     #   1 (what we have above):
-239     #     ECX = s
-240     #     EAX = s->write
-241     #     EDX = s->length
-242     #     # syscall
-243     #     ECX = lea ECX+EAX+12
-244     #     EDX = sub EDX EAX
-245     #
-246     #   2:
-247     #     ECX = s
-248     #     EDX = s->length
-249     #     ECX = &s->data
-250     #     # syscall
-251     #     ECX = add ECX, s->write
-252     #     EDX = sub EDX, s->write
-253     #
-254     # Not much to choose between the two? Option 2 performs a duplicate load to
-255     # use one less register, but doesn't increase the amount of spilling (ECX
-256     # and EDX must be used, and EAX must be clobbered anyway).
-257 
-258 # - tests
-259 
-260 test-read-single:
-261     # - write a single character into _test-stream, then read from it
-262     # clear-stream(_test-stream)
-263     # . . push args
-264     68/push  _test-stream/imm32
-265     # . . call
-266     e8/call  clear-stream/disp32
-267     # . . discard args
-268     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
-269     # clear-stream(_test-tmp-stream)
-270     # . . push args
-271     68/push  _test-tmp-stream/imm32
-272     # . . call
-273     e8/call  clear-stream/disp32
-274     # . . discard args
-275     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
-276     # write(_test-stream, "Ab")
-277     # . . push args
-278     68/push  "Ab"/imm32
-279     68/push  _test-stream/imm32
-280     # . . call
-281     e8/call  write/disp32
-282     # . . discard args
-283     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
-284     # EAX = read(_test-stream, _test-tmp-stream)
-285     # . . push args
-286     68/push  _test-tmp-stream/imm32
-287     68/push  _test-stream/imm32
-288     # . . call
-289     e8/call  read/disp32
-290     # . . discard args
-291     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
-292     # check-ints-equal(EAX, 2, msg)
-293     # . . push args
-294     68/push  "F - test-read-single: return EAX"/imm32
-295     68/push  2/imm32
-296     50/push-EAX
-297     # . . call
-298     e8/call  check-ints-equal/disp32
-299     # . . discard args
-300     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0xc/imm32         # add to ESP
-301     # check-stream-equal(_test-tmp-stream, "Ab", msg)
-302     # . . push args
-303     68/push  "F - test-read-single"/imm32
-304     68/push  "Ab"/imm32
-305     68/push  _test-tmp-stream/imm32
-306     # . . call
-307     e8/call  check-stream-equal/disp32
-308     # . . discard args
-309     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0xc/imm32         # add to ESP
-310     # end
-311     c3/return
-312 
-313 test-read-is-stateful:
-314     # - make two consecutive reads, check that their results are appended
-315     # clear-stream(_test-stream)
-316     # . . push args
-317     68/push  _test-stream/imm32
-318     # . . call
-319     e8/call  clear-stream/disp32
-320     # . . discard args
-321     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
-322     # clear-stream(_test-tmp-stream)
-323     # . . push args
-324     68/push  _test-tmp-stream/imm32
-325     # . . call
-326     e8/call  clear-stream/disp32
-327     # . . discard args
-328     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
-329     # write(_test-stream, "C")
-330     # . . push args
-331     68/push  "C"/imm32
-332     68/push  _test-stream/imm32
-333     # . . call
-334     e8/call  write/disp32
-335     # . . discard args
-336     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
-337     # read(_test-stream, _test-tmp-stream)
-338     # . . push args
-339     68/push  _test-tmp-stream/imm32
-340     68/push  _test-stream/imm32
-341     # . . call
-342     e8/call  read/disp32
-343     # . . discard args
-344     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
-345     # write(_test-stream, "D")
-346     # . . push args
-347     68/push  "D"/imm32
-348     68/push  _test-stream/imm32
-349     # . . call
-350     e8/call  write/disp32
-351     # . . discard args
-352     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
-353     # read(_test-stream, _test-tmp-stream)
-354     # . . push args
-355     68/push  _test-tmp-stream/imm32
-356     68/push  _test-stream/imm32
-357     # . . call
-358     e8/call  read/disp32
-359     # . . discard args
-360     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
-361     # check-stream-equal(_test-tmp-stream, "CD", msg)
-362     # . . push args
-363     68/push  "F - test-read-is-stateful"/imm32
-364     68/push  "CD"/imm32
-365     68/push  _test-tmp-stream/imm32
-366     # . . call
-367     e8/call  check-stream-equal/disp32
-368     # . . discard args
-369     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0xc/imm32         # add to ESP
-370     # end
-371     c3/return
-372 
-373 test-read-returns-0-on-end-of-file:
-374     # - read after hitting end-of-file, check that result is 0
-375     # setup
-376     # . clear-stream(_test-stream)
-377     # . . push args
-378     68/push  _test-stream/imm32
-379     # . . call
-380     e8/call  clear-stream/disp32
-381     # . . discard args
-382     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
-383     # . clear-stream(_test-tmp-stream)
-384     # . . push args
-385     68/push  _test-tmp-stream/imm32
-386     # . . call
-387     e8/call  clear-stream/disp32
-388     # . . discard args
-389     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
-390     # . write(_test-stream, "Ab")
-391     # . . push args
-392     68/push  "Ab"/imm32
-393     68/push  _test-stream/imm32
-394     # . . call
-395     e8/call  write/disp32
-396     # . . discard args
-397     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
-398     # first read gets to end-of-file
-399     # . read(_test-stream, _test-tmp-stream)
-400     # . . push args
-401     68/push  _test-tmp-stream/imm32
-402     68/push  _test-stream/imm32
-403     # . . call
-404     e8/call  read/disp32
-405     # . . discard args
-406     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
-407     # second read
-408     # . read(_test-stream, _test-tmp-stream)
-409     # . . push args
-410     68/push  _test-tmp-stream/imm32
-411     68/push  _test-stream/imm32
-412     # . . call
-413     e8/call  read/disp32
-414     # . . discard args
-415     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
-416     # check-ints-equal(EAX, 0, msg)
-417     # . . push args
-418     68/push  "F - test-read-returns-0-on-end-of-file"/imm32
-419     68/push  0/imm32
-420     50/push-EAX
-421     # . . call
-422     e8/call  check-ints-equal/disp32
-423     # . . discard args
-424     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0xc/imm32         # add to ESP
-425     # end
-426     c3/return
-427 
-428 == data
-429 
-430 _test-tmp-stream:
-431     # current write index
-432     0/imm32
-433     # current read index
-434     0/imm32
-435     # length
-436     8/imm32
-437     # data
-438     00 00 00 00 00 00 00 00  # 8 bytes
-439 
-440 # . . vim:nowrap:textwidth=0
-
- - - -- cgit 1.4.1-2-gfad0