7522 - bring back a few tests in .subx files

Even though baremetal has tests in SubX, they can only run in Mu
programs since the test harness is currently in a Mu layer. Baremetal
isn't really intended for running SubX programs at the moment. Is this a
step down the slippery slope towards C compilers that I complained about
in http://akkartik.name/akkartik-convivial-20200607.pdf?

5 files changed, 744 insertions, 5 deletions

diff --git a/baremetal/108write.subx b/baremetal/108write.subx
index 91a5e680..4f3b0b7f 100644
--- a/baremetal/108write.subx
+++ b/baremetal/108write.subx
@@ -1,3 +1,10 @@
+# write: write to in-memory streams
+#
+# A stream looks like this:
+#   read: int  # index at which to read next
+#   write: int  # index at which writes go
+#   data: (array byte)  # prefixed by size as usual
+
 == code
 #   instruction                     effective address                                                   register    displacement    immediate
 # . op          subop               mod             rm32          base        index         scale       r32
@@ -10,8 +17,6 @@ write:  # f: (addr stream byte), s: (addr array byte)
     # 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
-    # TODO: write to file
-    # otherwise, treat 'f' as a stream to append to
     # . save registers
     50/push-eax
     51/push-ecx
@@ -49,7 +54,88 @@ $write:end:
     5d/pop-to-ebp
     c3/return
 
-# TODO: bring in tests once we have check-ints-equal
+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
diff --git a/baremetal/109stream-equal.subx b/baremetal/109stream-equal.subx
new file mode 100644
index 00000000..8f6cf1bf
--- /dev/null
+++ b/baremetal/109stream-equal.subx
@@ -0,0 +1,595 @@
+# some primitives for checking stream contents
+
+== 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
+
+# compare all the data in a stream (ignoring the read pointer)
+stream-data-equal?:  # f: (addr stream byte), s: (addr array byte) -> result/eax: boolean
+    # . 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
+    56/push-esi
+    57/push-edi
+    # esi = f
+    8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .             .           6/r32/esi   8/disp8         .                 # copy *(ebp+8) to esi
+    # eax = f->write
+    8b/copy                         0/mod/indirect  6/rm32/esi    .           .             .           0/r32/eax   .               .                 # copy *esi to eax
+    # var maxf/edx: (addr byte) = &f->data[f->write]
+    8d/copy-address                 1/mod/*+disp8   4/rm32/sib    6/base/esi  0/index/eax   .           2/r32/edx   0xc/disp8       .                 # copy esi+eax+12 to edx
+    # var currf/esi: (addr byte) = f->data
+    81          0/subop/add         3/mod/direct    6/rm32/esi    .           .             .           .           .               0xc/imm32         # add to esi
+    # edi = s
+    8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .             .           7/r32/edi   0xc/disp8       .                 # copy *(ebp+12) to edi
+$stream-data-equal?:compare-sizes:
+    # if (f->write != s->size) return false
+    39/compare                      0/mod/indirect  7/rm32/edi    .           .             .           0/r32/eax   .               .                 # compare *edi and eax
+    75/jump-if-!=  $stream-data-equal?:false/disp8
+    # var currs/edi: (addr byte) = s->data
+    81          0/subop/add         3/mod/direct    7/rm32/edi    .           .             .           .           .               4/imm32           # add to edi
+    # var eax: byte = 0
+    31/xor                          3/mod/direct    0/rm32/eax    .           .             .           0/r32/eax   .               .                 # clear eax
+    # var ecx: byte = 0
+    31/xor                          3/mod/direct    1/rm32/ecx    .           .             .           1/r32/ecx   .               .                 # clear ecx
+$stream-data-equal?:loop:
+    # if (currf >= maxf) return true
+    39/compare                      3/mod/direct    6/rm32/esi    .           .             .           2/r32/edx   .               .                 # compare esi with edx
+    73/jump-if-addr>=  $stream-data-equal?:true/disp8
+    # AL = *currs
+    8a/copy-byte                    0/mod/indirect  6/rm32/esi    .           .             .           0/r32/AL    .               .                 # copy byte at *esi to AL
+    # CL = *curr
+    8a/copy-byte                    0/mod/indirect  7/rm32/edi    .           .             .           1/r32/CL    .               .                 # copy byte at *edi to CL
+    # if (eax != ecx) return false
+    39/compare                      3/mod/direct    0/rm32/eax    .           .             .           1/r32/ecx   .               .                 # compare eax and ecx
+    75/jump-if-!=  $stream-data-equal?:false/disp8
+    # ++f
+    46/increment-esi
+    # ++curr
+    47/increment-edi
+    eb/jump $stream-data-equal?:loop/disp8
+$stream-data-equal?:false:
+    b8/copy-to-eax  0/imm32
+    eb/jump  $stream-data-equal?:end/disp8
+$stream-data-equal?:true:
+    b8/copy-to-eax  1/imm32
+$stream-data-equal?:end:
+    # . restore registers
+    5f/pop-to-edi
+    5e/pop-to-esi
+    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
+
+test-stream-data-equal:
+    # . prologue
+    55/push-ebp
+    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
+    # 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, "Abc")
+    # . . push args
+    68/push  "Abc"/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
+    # eax = stream-data-equal?(_test-stream, "Abc")
+    # . . push args
+    68/push  "Abc"/imm32
+    68/push  _test-stream/imm32
+    # . . call
+    e8/call  stream-data-equal?/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
+    # check-ints-equal(eax, 1, msg)
+    # . . push args
+    68/push  "F - test-stream-data-equal"/imm32
+    68/push  1/imm32
+    50/push-eax
+    # . . call
+    e8/call  check-ints-equal/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
+    # . epilogue
+    89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
+    5d/pop-to-ebp
+    c3/return
+
+test-stream-data-equal-2:
+    # . prologue
+    55/push-ebp
+    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
+    # 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, "Abc")
+    # . . push args
+    68/push  "Abc"/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
+    # eax = stream-data-equal?(_test-stream, "Abd")
+    # . . push args
+    68/push  "Abd"/imm32
+    68/push  _test-stream/imm32
+    # . . call
+    e8/call  stream-data-equal?/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
+    # check-ints-equal(eax, 0, msg)
+    # . . push args
+    68/push  "F - test-stream-data-equal-2"/imm32
+    68/push  0/imm32
+    50/push-eax
+    # . . call
+    e8/call  check-ints-equal/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
+    # . epilogue
+    89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
+    5d/pop-to-ebp
+    c3/return
+
+test-stream-data-equal-size-check:
+    # . prologue
+    55/push-ebp
+    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
+    # 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, "Abc")
+    # . . push args
+    68/push  "Abc"/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
+    # eax = stream-data-equal?(_test-stream, "Abcd")
+    # . . push args
+    68/push  "Abcd"/imm32
+    68/push  _test-stream/imm32
+    # . . call
+    e8/call  stream-data-equal?/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
+    # check-ints-equal(eax, 0, msg)
+    # . . push args
+    68/push  "F - test-stream-data-equal-size-check"/imm32
+    68/push  0/imm32
+    50/push-eax
+    # . . call
+    e8/call  check-ints-equal/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
+    # . epilogue
+    89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
+    5d/pop-to-ebp
+    c3/return
+
+# helper for later tests
+check-stream-equal:  # f: (addr stream byte), s: (addr array byte), msg: (addr array byte)
+    # . prologue
+    55/push-ebp
+    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
+    # . save registers
+    50/push-eax
+    # eax = stream-data-equal?(f, s)
+    # . . push args
+    ff          6/subop/push        1/mod/*+disp8   5/rm32/ebp    .           .             .           .           0xc/disp8       .                 # push *(ebp+12)
+    ff          6/subop/push        1/mod/*+disp8   5/rm32/ebp    .           .             .           .           8/disp8         .                 # push *(ebp+8)
+    # . . call
+    e8/call  stream-data-equal?/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
+    # check-ints-equal(eax, 1, msg)
+    # . . push args
+    ff          6/subop/push        1/mod/*+disp8   5/rm32/ebp    .           .             .           .           0x10/disp8      .                 # push *(ebp+16)
+    68/push  1/imm32
+    50/push-eax
+    # . . call
+    e8/call  check-ints-equal/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
+$check-stream-equal:end:
+    # . restore registers
+    58/pop-to-eax
+    # . epilogue
+    89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
+    5d/pop-to-ebp
+    c3/return
+
+# scan the next line until newline starting from f->read and compare it with
+# 's' (ignoring the trailing newline)
+# on success, set f->read to after the next newline
+# on failure, leave f->read unmodified
+# this function is usually used only in tests, so we repeatedly write f->read
+next-stream-line-equal?:  # f: (addr stream byte), s: (addr array byte) -> result/eax: boolean
+    # pseudocode:
+    #   currf = f->read  # bound: f->write
+    #   currs = 0  # bound: s->size
+    #   while true
+    #     if currf >= f->write
+    #       return currs >= s->size
+    #     if f[currf] == '\n'
+    #       ++currf
+    #       return currs >= s->size
+    #     if (currs >= s->size) return false  # the current line of f still has data to match
+    #     if (f[currf] != s[currs]) return false
+    #     ++currf
+    #     ++currs
+    #
+    # collapsing the two branches that can return true:
+    #   currf = f->read  # bound: f->write
+    #   currs = 0  # bound: s->size
+    #   while true
+    #     if (currf >= f->write) break
+    #     if (f[currf] == '\n') break
+    #     if (currs >= s->size) return false  # the current line of f still has data to match
+    #     if (f[currf] != s[currs]) return false
+    #     ++currf
+    #     ++currs
+    #   ++currf  # skip '\n'
+    #   return currs >= s->size
+    # Here the final `++currf` is sometimes unnecessary (if we're already at the end of the stream)
+    #
+    # registers:
+    #   f: esi
+    #   s: edi
+    #   currf: ecx
+    #   currs: edx
+    #   f[currf]: eax
+    #   s[currs]: ebx
+    #
+    # . 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
+    56/push-esi
+    57/push-edi
+    # esi = f
+    8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .             .           6/r32/esi   8/disp8         .                 # copy *(ebp+8) to esi
+    # var currf/ecx: int = f->read
+    8b/copy                         1/mod/*+disp8   6/rm32/esi    .           .             .           1/r32/ecx   4/disp8         .                 # copy *(esi+4) to ecx
+    # edi = s
+    8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .             .           7/r32/edi   0xc/disp8       .                 # copy *(ebp+12) to edi
+    # var currs/edx: int = 0
+    31/xor                          3/mod/direct    2/rm32/edx    .           .             .           2/r32/edx   .               .                 # clear edx
+    # var c1/eax: byte = 0
+    31/xor                          3/mod/direct    0/rm32/eax    .           .             .           0/r32/eax   .               .                 # clear eax
+    # var c2/ebx: byte = 0
+    31/xor                          3/mod/direct    3/rm32/ebx    .           .             .           3/r32/ebx   .               .                 # clear ebx
+$next-stream-line-equal?:loop:
+    # if (currf >= f->write) break
+    3b/compare                      0/mod/indirect  6/rm32/esi    .           .             .           1/r32/ecx   .               .                 # compare ecx with *esi
+    7d/jump-if->=  $next-stream-line-equal?:break/disp8
+    # c1 = f->data[f->read]
+    8a/copy-byte                    1/mod/*+disp8   4/rm32/sib    6/base/esi  1/index/ecx   .           0/r32/AL    0xc/disp8       .                 # copy byte at *(esi+ecx+12) to AL
+    # if (c1 == '\n') break
+    3d/compare-eax-and  0xa/imm32/newline
+    74/jump-if-=  $next-stream-line-equal?:break/disp8
+    # if (currs >= s->size) return false
+    3b/compare                      0/mod/indirect  7/rm32/edi    .           .             .           2/r32/edx   .               .                 # compare edx with *edi
+    7d/jump-if->=  $next-stream-line-equal?:false/disp8
+    # c2 = s->data[currs]
+    8a/copy-byte                    1/mod/*+disp8   4/rm32/sib    7/base/edi  2/index/edx   .           3/r32/BL    4/disp8         .                 # copy byte at *(edi+edx+4) to BL
+    # if (c1 != c2) return false
+    39/compare                      3/mod/direct    0/rm32/eax    .           .             .           3/r32/ebx   .               .                 # compare eax and ebx
+    75/jump-if-!=  $next-stream-line-equal?:false/disp8
+    # ++currf
+    41/increment-ecx
+    # ++currs
+    42/increment-edx
+    eb/jump $next-stream-line-equal?:loop/disp8
+$next-stream-line-equal?:break:
+    # ++currf
+    41/increment-ecx
+    # if (currs >= s->size) return true
+    3b/compare                      0/mod/indirect  7/rm32/edi    .           .             .           2/r32/edx   .               .                 # compare edx with *edi
+    7c/jump-if-<  $next-stream-line-equal?:false/disp8
+$next-stream-line-equal?:true:
+    b8/copy-to-eax  1/imm32
+    # persist f->read on success
+    89/copy                         1/mod/*+disp8   6/rm32/esi    .           .             .           1/r32/ecx   4/disp8         .                 # copy ecx to *(esi+4)
+    eb/jump  $next-stream-line-equal?:end/disp8
+$next-stream-line-equal?:false:
+    b8/copy-to-eax  0/imm32
+$next-stream-line-equal?:end:
+    # . restore registers
+    5f/pop-to-edi
+    5e/pop-to-esi
+    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
+
+test-next-stream-line-equal-stops-at-newline:
+    # . prologue
+    55/push-ebp
+    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
+    # 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, "Abc\ndef")
+    # . . push args
+    68/push  "Abc\ndef"/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
+    # eax = next-stream-line-equal?(_test-stream, "Abc")
+    # . . push args
+    68/push  "Abc"/imm32
+    68/push  _test-stream/imm32
+    # . . call
+    e8/call  next-stream-line-equal?/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
+    # check-ints-equal(eax, 1, msg)
+    # . . push args
+    68/push  "F - test-next-stream-line-equal-stops-at-newline"/imm32
+    68/push  1/imm32
+    50/push-eax
+    # . . call
+    e8/call  check-ints-equal/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
+    # . epilogue
+    89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
+    5d/pop-to-ebp
+    c3/return
+
+test-next-stream-line-equal-stops-at-newline-2:
+    # . prologue
+    55/push-ebp
+    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
+    # 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, "Abc\ndef")
+    # . . push args
+    68/push  "Abc\ndef"/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
+    # eax = next-stream-line-equal?(_test-stream, "def")
+    # . . push args
+    68/push  "def"/imm32
+    68/push  _test-stream/imm32
+    # . . call
+    e8/call  next-stream-line-equal?/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
+    # check-ints-equal(eax, 0, msg)
+    # . . push args
+    68/push  "F - test-next-stream-line-equal-stops-at-newline-2"/imm32
+    68/push  0/imm32
+    50/push-eax
+    # . . call
+    e8/call  check-ints-equal/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
+    # . epilogue
+    89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
+    5d/pop-to-ebp
+    c3/return
+
+test-next-stream-line-equal-skips-newline:
+    # . prologue
+    55/push-ebp
+    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
+    # 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, "Abc\ndef\n")
+    # . . push args
+    68/push  "Abc\ndef\n"/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
+    # next-stream-line-equal?(_test-stream, "Abc")
+    # . . push args
+    68/push  "Abc"/imm32
+    68/push  _test-stream/imm32
+    # . . call
+    e8/call  next-stream-line-equal?/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
+    # eax = next-stream-line-equal?(_test-stream, "def")
+    # . . push args
+    68/push  "def"/imm32
+    68/push  _test-stream/imm32
+    # . . call
+    e8/call  next-stream-line-equal?/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
+    # check-ints-equal(eax, 1, msg)
+    # . . push args
+    68/push  "F - test-next-stream-line-equal-skips-newline"/imm32
+    68/push  1/imm32
+    50/push-eax
+    # . . call
+    e8/call  check-ints-equal/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
+    # . epilogue
+    89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
+    5d/pop-to-ebp
+    c3/return
+
+test-next-stream-line-equal-handles-final-line:
+    # . prologue
+    55/push-ebp
+    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
+    # 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, "Abc\ndef")
+    # . . push args
+    68/push  "Abc\ndef"/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
+    # next-stream-line-equal?(_test-stream, "Abc")
+    # . . push args
+    68/push  "Abc"/imm32
+    68/push  _test-stream/imm32
+    # . . call
+    e8/call  next-stream-line-equal?/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
+    # eax = next-stream-line-equal?(_test-stream, "def")
+    # . . push args
+    68/push  "def"/imm32
+    68/push  _test-stream/imm32
+    # . . call
+    e8/call  next-stream-line-equal?/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
+    # check-ints-equal(eax, 1, msg)
+    # . . push args
+    68/push  "F - test-next-stream-line-equal-skips-newline"/imm32
+    68/push  1/imm32
+    50/push-eax
+    # . . call
+    e8/call  check-ints-equal/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
+    # . epilogue
+    89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
+    5d/pop-to-ebp
+    c3/return
+
+test-next-stream-line-equal-always-fails-after-Eof:
+    # . prologue
+    55/push-ebp
+    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
+    # 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 nothing
+    # eax = next-stream-line-equal?(_test-stream, "")
+    # . . push args
+    68/push  ""/imm32
+    68/push  _test-stream/imm32
+    # . . call
+    e8/call  next-stream-line-equal?/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
+    # check-ints-equal(eax, 0, msg)
+    # . . push args
+    68/push  "F - test-next-stream-line-equal-always-fails-after-Eof"/imm32
+    68/push  1/imm32
+    50/push-eax
+    # . . call
+    e8/call  check-ints-equal/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
+    # eax = next-stream-line-equal?(_test-stream, "")
+    # . . push args
+    68/push  ""/imm32
+    68/push  _test-stream/imm32
+    # . . call
+    e8/call  next-stream-line-equal?/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
+    # check-ints-equal(eax, 0, msg)
+    # . . push args
+    68/push  "F - test-next-stream-line-equal-always-fails-after-Eof/2"/imm32
+    68/push  1/imm32
+    50/push-eax
+    # . . call
+    e8/call  check-ints-equal/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
+    # . epilogue
+    89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
+    5d/pop-to-ebp
+    c3/return
+
+# helper for later tests
+check-next-stream-line-equal:  # f: (addr stream byte), s: (addr array byte), msg: (addr array byte)
+    # . prologue
+    55/push-ebp
+    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
+    # . save registers
+    50/push-eax
+    # eax = next-stream-line-equal?(f, s)
+    # . . push args
+    ff          6/subop/push        1/mod/*+disp8   5/rm32/ebp    .           .             .           .           0xc/disp8       .                 # push *(ebp+12)
+    ff          6/subop/push        1/mod/*+disp8   5/rm32/ebp    .           .             .           .           8/disp8         .                 # push *(ebp+8)
+    # . . call
+    e8/call  next-stream-line-equal?/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
+    # check-ints-equal(eax, 1, msg)
+    # . . push args
+    ff          6/subop/push        1/mod/*+disp8   5/rm32/ebp    .           .             .           .           0x10/disp8      .                 # push *(ebp+16)
+    68/push  1/imm32
+    50/push-eax
+    # . . call
+    e8/call  check-ints-equal/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
+    # . restore registers
+    58/pop-to-eax
+    # . 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
diff --git a/baremetal/112read-byte.subx b/baremetal/112read-byte.subx
index e6a54fdd..f86498bb 100644
--- a/baremetal/112read-byte.subx
+++ b/baremetal/112read-byte.subx
@@ -3,8 +3,6 @@
 # . 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
 
-# TODO: read-byte-buffered
-
 # Return next byte value in eax, with top 3 bytes cleared.
 # Abort on reaching end of stream.
 read-byte:  # s: (addr stream byte) -> result/eax: byte
diff --git a/baremetal/115write-byte.subx b/baremetal/115write-byte.subx
index d69663bc..af32f610 100644
--- a/baremetal/115write-byte.subx
+++ b/baremetal/115write-byte.subx
@@ -35,4 +35,34 @@ $append-byte:end:
     5d/pop-to-ebp
     c3/return
 
+test-append-byte-single:
+    # - check that append-byte writes to first byte of 'file'
+    # setup
+    # . 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
+    # append-byte(_test-stream, 'A')
+    # . . push args
+    68/push  0x41/imm32
+    68/push  _test-stream/imm32
+    # . . call
+    e8/call  append-byte/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
+    # check-stream-equal(_test-stream, "A", msg)
+    # . . push args
+    68/push  "F - test-append-byte-single"/imm32
+    68/push  "A"/imm32
+    68/push  _test-stream/imm32
+    # . . call
+    e8/call  check-stream-equal/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
+    # . end
+    c3/return
+
 # . . vim:nowrap:textwidth=0
diff --git a/baremetal/120allocate.subx b/baremetal/120allocate.subx
index 2aaa8e75..95356e7f 100644
--- a/baremetal/120allocate.subx
+++ b/baremetal/120allocate.subx
@@ -50,4 +50,34 @@ $zero-out:end:
     5d/pop-to-ebp
     c3/return
 
+test-zero-out:
+    # . prologue
+    55/push-ebp
+    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
+    # region/ecx = 34, 35, 36, 37
+    68/push  0x37363534/imm32
+    89/copy                         3/mod/direct    1/rm32/ecx    .           .             .           4/r32/esp   .               .                 # copy esp to ecx
+    # zero-out(ecx, 3)
+    # . . push args
+    68/push  3/imm32/size
+    51/push-ecx
+    # . . call
+    e8/call  zero-out/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
+    # first 3 bytes cleared, fourth left alone
+    # . check-ints-equal(*ecx, 0x37000000, msg)
+    # . . push args
+    68/push  "F - test-zero-out"/imm32
+    68/push  0x37000000/imm32
+    ff          6/subop/push        0/mod/indirect  1/rm32/ecx    .           .             .           .           .               .                 # push *ecx
+    # . . call
+    e8/call  check-ints-equal/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
+    # . 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