4850

2 files changed, 137 insertions, 1 deletions

diff --git a/subx/apps/hex b/subx/apps/hex
index 299151cc..b6c2afea 100644
--- a/subx/apps/hex
+++ b/subx/apps/hex
Binary files differdiff --git a/subx/apps/hex.subx b/subx/apps/hex.subx
index 4bc56fcf..f73a9a66 100644
--- a/subx/apps/hex.subx
+++ b/subx/apps/hex.subx
@@ -44,6 +44,7 @@
 #?     e8/call test-scan-next-byte/disp32
 #?     e8/call test-scan-next-byte-handles-eof/disp32
 #?     e8/call test-scan-next-byte-skips-comment/disp32
+#?     e8/call test-convert-next-hex-byte/disp32
     e8/call  run-tests/disp32
     8b/copy                         0/mod/indirect  5/rm32/.disp32            .             .           3/r32/EBX   Num-test-failures/disp32          # copy *Num-test-failures to EBX
     eb/jump  $main:end/disp8
@@ -96,7 +97,7 @@ convert-next-hex-byte:  # in : (address buffered-file), err : (address buffered-
     #   if (EAX == 0xffffffff) return
     #   ECX = EAX
     #   EAX = scan-next-byte(in, err, ed)
-    #   if (EAX == 0xffffffff) error("partial byte found")
+    #   if (EAX == 0xffffffff) error("partial byte found.")
     #   ECX = (ECX << 8) | EAX
     #   return
     #
@@ -104,13 +105,148 @@ convert-next-hex-byte:  # in : (address buffered-file), err : (address buffered-
     55/push-EBP
     89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
     # . save registers
+    51/push-ECX
+    # EAX = scan-next-byte(in, err, ed)
+    # . . push args
+    ff          6/subop/push        1/mod/*+disp8   4/rm32/sib    5/base/EBP  4/index/none  .           .           0x10/disp8      .                 # push *(EBP+16)
+    ff          6/subop/push        1/mod/*+disp8   4/rm32/sib    5/base/EBP  4/index/none  .           .           0xc/disp8       .                 # push *(EBP+12)
+    ff          6/subop/push        1/mod/*+disp8   4/rm32/sib    5/base/EBP  4/index/none  .           .           8/disp8         .                 # push *(EBP+8)
+    # . . call
+    e8/call  scan-next-byte/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0xc/imm32         # add to ESP
+    # if (EAX == 0xffffffff) return
+    81          7/subop/compare     3/mod/direct    0/rm32/EAX    .           .             .           .           .               0xffffffff/imm32  # compare EAX
+    74/jump-if-equal  $convert-next-hex-byte:end/disp8
+    # ECX = EAX
+    89/copy                         3/mod/direct    1/rm32/ECX    .           .             .           0/r32/EAX   .               .                 # copy EAX to ECX
+    # EAX = scan-next-byte(in, err, ed)
+    # . . push args
+    ff          6/subop/push        1/mod/*+disp8   4/rm32/sib    5/base/EBP  4/index/none  .           .           0x10/disp8      .                 # push *(EBP+16)
+    ff          6/subop/push        1/mod/*+disp8   4/rm32/sib    5/base/EBP  4/index/none  .           .           0xc/disp8       .                 # push *(EBP+12)
+    ff          6/subop/push        1/mod/*+disp8   4/rm32/sib    5/base/EBP  4/index/none  .           .           8/disp8         .                 # push *(EBP+8)
+    # . . call
+    e8/call  scan-next-byte/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0xc/imm32         # add to ESP
+    # if (EAX == 0xffffffff) error(ed, err, "partial byte found.")
+    81          7/subop/compare     3/mod/direct    0/rm32/EAX    .           .             .           .           .               0xffffffff/imm32  # compare EAX
+    75/jump-if-not-equal  $convert-next-hex-byte:convert/disp8
+    # . error-byte(ed, err, msg, '.')  # reusing error-byte to avoid creating _yet_ another helper
+    # . . push args
+    68/push  0x2e/imm32/period/dummy
+    68/push  "convert-next-hex-byte: partial byte found"/imm32
+    ff          6/subop/push        1/mod/*+disp8   4/rm32/sib    5/base/EBP  4/index/none  .           .           0xc/disp8       .                 # push *(EBP+12)
+    ff          6/subop/push        1/mod/*+disp8   4/rm32/sib    5/base/EBP  4/index/none  .           .           0x10/disp8      .                 # push *(EBP+16)
+    # . . call
+    e8/call  error-byte/disp32  # never returns
+$convert-next-hex-byte:convert:
+    # EAX = (EAX << 8) | ECX
+    # . EAX <<= 8
+    c1/shift    4/subop/left        3/mod/direct    0/rm32/EAX    .           .             .           .           .               8/imm8            # shift EAX left by 8 bits
+    # . EAX |= ECX
+    09/or                           3/mod/direct    0/rm32/EAX    .           .             .           1/r32/ECX   .               .                 # EAX = bitwise OR with ECX
 $convert-next-hex-byte:end:
     # . restore registers
+    59/pop-to-ECX
     # . epilog
     89/copy                         3/mod/direct    4/rm32/ESP    .           .             .           5/r32/EBP   .               .                 # copy EBP to ESP
     5d/pop-to-EBP
     c3/return
 
+test-convert-next-hex-byte:
+    # - check that the first two bytes of the input are assembled into the resulting number
+    # This test uses exit-descriptors. Use EBP for setting up local variables.
+    55/push-EBP
+    89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
+    # clear all streams
+    # . 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
+    # . clear-stream(_test-buffered-file+4)
+    # . . push args
+    b8/copy-to-EAX  _test-buffered-file/imm32
+    05/add-to-EAX  4/imm32
+    50/push-EAX
+    # . . call
+    e8/call  clear-stream/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
+    # . clear-stream(_test-error-stream)
+    # . . push args
+    68/push  _test-error-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
+    # initialize '_test-stream' to "abc"
+    # . 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
+    # initialize exit-descriptor 'ed' for the call to 'convert-next-hex-byte' below
+    # . var ed/ECX : exit-descriptor
+    81          5/subop/subtract    3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # subtract from ESP
+    8d/copy-address                 0/mod/indirect  4/rm32/sib    4/base/ESP  4/index/none  .           1/r32/ECX   .               .                 # copy ESP to ECX
+    # . tailor-exit-descriptor(ed, 12)
+    # . . push args
+    68/push  0xc/imm32/nbytes-of-args-for-convert-next-hex-byte
+    51/push-ECX/ed
+    # . . call
+    e8/call  tailor-exit-descriptor/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
+    # EAX = convert-next-hex-byte(_test-buffered-file, _test-error-stream, ed)
+    # . . push args
+    51/push-ECX/ed
+    68/push  _test-error-stream/imm32
+    68/push  _test-buffered-file/imm32
+    # . . call
+    e8/call  convert-next-hex-byte/disp32
+    # registers except ESP may be clobbered at this point
+    # pop args to convert-next-hex-bytes
+    # . . discard first 2 args
+    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
+    # . . restore ed
+    59/pop-to-ECX
+    # check that convert-next-hex-byte didn't abort
+    # . check-ints-equal(ed->value, 0, msg)
+    # . . push args
+    68/push  "F - test-convert-next-hex-byte: unexpected abort"/imm32
+    68/push  0/imm32
+    # . . push ed->value
+    ff          6/subop/push        1/mod/*+disp8   1/rm32/ECX    .           .             .           .           4/disp8         .                 # push *(ECX+4)
+    # . . call
+    e8/call  check-ints-equal/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0xc/imm32         # add to ESP
+    # return if abort
+    81          7/subop/compare     1/mod/*+disp8   1/rm32/ECX    .           .             .           .           4/disp8         0/imm32           # compare *(ECX+4)
+    75/jump-if-not-equal  $test-convert-next-hex-byte:end/disp8
+    # check-ints-equal(EAX, 0x61/a 0x62/b, msg)
+    # . . push args
+    68/push  "F - test-convert-next-hex-byte"/imm32
+    68/push  0x6261/imm32/ab
+    50/push-EAX
+    # . . call
+    e8/call  check-ints-equal/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0xc/imm32         # add to ESP
+$test-convert-next-hex-byte:end:
+    # . epilog
+    # don't restore ESP from EBP; manually reclaim locals
+    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
+    5d/pop-to-EBP
+    c3/return
+
 # read whitespace until a hex byte, and return it
 # return 0xffffffff if file ends without finding a hex byte
 # on '#' skip all bytes until newline