mu/baremetal/108write.subx
Kartik Agaram 49424b1933 7523
There's a dependency cycle here:

- draw-grapheme (Mu) uses read-grapheme (Mu) to be unicode-aware.
- read-grapheme uses read-byte (SubX). Streams are a fundamental data
  structure in Mu. For the Mu compiler to be able to reason about the
  safety of stream operations, they need to be an opaque type. All
  stream primitives are written in SubX. To manipulate a stream's
  internals we force people to reach for SubX. That way if there's no
  SubX code there's confidence that things are safe.
- read-byte and other stream operations have unit tests, like they
  should. The unit tests need to print data to screen when say a test
  fails. To do this they use various check- functions (SubX) that take a
  string argument.
- Printing a string to screen uses draw-grapheme (Mu).

Perhaps I should maintain variants of drawing primitives that operate
only on ASCII.
2021-01-15 21:22:33 -08:00

221 lines
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# write: write to in-memory streams
#
# We need to do this in machine code because streams need to be opaque types,
# and we don't yet support opaque types in Mu.
== code
# instruction effective address register displacement immediate
# . op subop mod rm32 base index scale r32
# . 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
write: # f: (addr stream byte), s: (addr array byte)
# . prologue
55/push-ebp
89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp
# if (s == 0) return
81 7/subop/compare 1/mod/*+disp8 5/rm32/ebp . . . . 0xc/disp8 0/imm32 # compare *(ebp+12)
74/jump-if-= $write:end/disp8
# . save registers
50/push-eax
51/push-ecx
52/push-edx
53/push-ebx
# ecx = f
8b/copy 1/mod/*+disp8 5/rm32/ebp . . 1/r32/ecx 8/disp8 . # copy *(ebp+8) to ecx
# edx = f->write
8b/copy 0/mod/indirect 1/rm32/ecx . . . 2/r32/edx . . # copy *ecx to edx
# ebx = f->size
8b/copy 1/mod/*+disp8 1/rm32/ecx . . . 3/r32/ebx 8/disp8 . # copy *(ecx+8) to ebx
# eax = _append-3(&f->data[f->write], &f->data[f->size], s)
# . . push s
ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 0xc/disp8 . # push *(ebp+12)
# . . push &f->data[f->size]
8d/copy-address 1/mod/*+disp8 4/rm32/sib 1/base/ecx 3/index/ebx . 3/r32/ebx 0xc/disp8 . # copy ecx+ebx+12 to ebx
53/push-ebx
# . . push &f->data[f->write]
8d/copy-address 1/mod/*+disp8 4/rm32/sib 1/base/ecx 2/index/edx . 3/r32/ebx 0xc/disp8 . # copy ecx+edx+12 to ebx
53/push-ebx
# . . call
e8/call _append-3/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
# f->write += eax
01/add 0/mod/indirect 1/rm32/ecx . . . 0/r32/eax . . # add eax to *ecx
# . restore registers
5b/pop-to-ebx
5a/pop-to-edx
59/pop-to-ecx
58/pop-to-eax
$write:end:
# . epilogue
89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp
5d/pop-to-ebp
c3/return
test-write-single:
# clear-stream(_test-stream)
# . . push args
68/push _test-stream/imm32
# . . call
e8/call clear-stream/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 4/imm32 # add to esp
# write(_test-stream, "Ab")
# . . push args
68/push "Ab"/imm32
68/push _test-stream/imm32
# . . call
e8/call write/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
# check-ints-equal(*_test-stream->data, 41/A 62/b 00 00, msg)
# . . push args
68/push "F - test-write-single"/imm32
68/push 0x006241/imm32/Ab
# . . push *_test-stream->data
b8/copy-to-eax _test-stream/imm32
ff 6/subop/push 1/mod/*+disp8 0/rm32/eax . . . . 0xc/disp8 . # push *(eax+12)
# . . call
e8/call check-ints-equal/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
# end
c3/return
test-write-appends:
# clear-stream(_test-stream)
# . . push args
68/push _test-stream/imm32
# . . call
e8/call clear-stream/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 4/imm32 # add to esp
# write(_test-stream, "C")
# . . push args
68/push "C"/imm32
68/push _test-stream/imm32
# . . call
e8/call write/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
# write(_test-stream, "D")
# . . push args
68/push "D"/imm32
68/push _test-stream/imm32
# . . call
e8/call write/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
# check-ints-equal(*_test-stream->data, 43/C 44/D 00 00, msg)
# . . push args
68/push "F - test-write-appends"/imm32
68/push 0x00004443/imm32/C-D
# . . push *_test-stream->data
b8/copy-to-eax _test-stream/imm32
ff 6/subop/push 1/mod/*+disp8 0/rm32/eax . . . . 0xc/disp8 . # push *(eax+12)
# . . call
e8/call check-ints-equal/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
# end
c3/return
== data
_test-stream: # (stream byte)
# current write index
0/imm32
# current read index
0/imm32
# size
0x10/imm32
# data (2 lines x 8 bytes/line)
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
== code
# 3-argument variant of _append
_append-3: # out: (addr byte), outend: (addr byte), s: (addr array byte) -> num_bytes_appended/eax
# . prologue
55/push-ebp
89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp
# . save registers
51/push-ecx
# eax = _append-4(out, outend, &s->data[0], &s->data[s->size])
# . . push &s->data[s->size]
8b/copy 1/mod/*+disp8 5/rm32/ebp . . 0/r32/eax 0x10/disp8 . # copy *(ebp+16) to eax
8b/copy 0/mod/indirect 0/rm32/eax . . . 1/r32/ecx . . # copy *eax to ecx
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
51/push-ecx
# . . push &s->data[0]
8d/copy-address 1/mod/*+disp8 0/rm32/eax . . . 1/r32/ecx 4/disp8 . # copy eax+4 to ecx
51/push-ecx
# . . push outend
ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 0xc/disp8 . # push *(ebp+12)
# . . push out
ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 8/disp8 . # push *(ebp+8)
# . . call
e8/call _append-4/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0x10/imm32 # add to esp
$_append-3:end:
# . restore registers
59/pop-to-ecx
# . epilogue
89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp
5d/pop-to-ebp
c3/return
# 4-argument variant of _append
_append-4: # out: (addr byte), outend: (addr byte), in: (addr byte), inend: (addr byte) -> num_bytes_appended/eax: int
# . prologue
55/push-ebp
89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp
# . save registers
51/push-ecx
52/push-edx
53/push-ebx
56/push-esi
57/push-edi
# num_bytes_appended = 0
b8/copy-to-eax 0/imm32
# edi = out
8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 7/r32/edi 8/disp8 . # copy *(ebp+8) to edi
# edx = outend
8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 2/r32/edx 0xc/disp8 . # copy *(ebp+12) to edx
# esi = in
8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 6/r32/esi 0x10/disp8 . # copy *(ebp+16) to esi
# ecx = inend
8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 1/r32/ecx 0x14/disp8 . # copy *(ebp+20) to ecx
$_append-4:loop:
# if (in >= inend) break
39/compare 3/mod/direct 6/rm32/esi . . . 1/r32/ecx . . # compare esi with ecx
73/jump-if-addr>= $_append-4:end/disp8
# if (out >= outend) abort # just to catch test failures fast
39/compare 3/mod/direct 7/rm32/edi . . . 2/r32/edx . . # compare edi with edx
73/jump-if-addr>= $_append-4:end/disp8 # TODO: abort
# *out = *in
8a/copy-byte 0/mod/indirect 6/rm32/esi . . . 3/r32/BL . . # copy byte at *esi to BL
88/copy-byte 0/mod/indirect 7/rm32/edi . . . 3/r32/BL . . # copy byte at BL to *edi
# ++num_bytes_appended
40/increment-eax
# ++in
46/increment-esi
# ++out
47/increment-edi
eb/jump $_append-4:loop/disp8
$_append-4:end:
# . restore registers
5f/pop-to-edi
5e/pop-to-esi
5b/pop-to-ebx
5a/pop-to-edx
59/pop-to-ecx
# . epilogue
89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp
5d/pop-to-ebp
c3/return
# . . vim:nowrap:textwidth=0