4911

11 files changed, 223 insertions, 21 deletions

diff --git a/subx/052kernel-string-equal.subx b/subx/052kernel-string-equal.subx
index 67e9695e..5ee7d5ef 100644
--- a/subx/052kernel-string-equal.subx
+++ b/subx/052kernel-string-equal.subx
@@ -29,16 +29,6 @@
 # compare a null-terminated ascii string with a more idiomatic length-prefixed byte array
 # reason for the name: the only place we should have null-terminated ascii strings is from commandline args
 kernel-string-equal:  # s : null-terminated ascii string, benchmark : length-prefixed ascii string -> EAX : boolean
-    # . prolog
-    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
-
     # pseudocode:
     #   initialize n = b->length
     #   initialize s1 = s
@@ -53,6 +43,15 @@ kernel-string-equal:  # s : null-terminated ascii string, benchmark : length-pre
     #       return false
     #   return *s1 == 0
     #
+    # . prolog
+    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
     # initialize s into EDI
     8b/copy                         1/mod/*+disp8   5/rm32/EBP    .           .             .           7/r32/EDI   8/disp8         .                 # copy *(EBP+8) to EDI
     # initialize benchmark length n into EDX
diff --git a/subx/054string-equal.subx b/subx/054string-equal.subx
index fe6dd17b..1854403c 100644
--- a/subx/054string-equal.subx
+++ b/subx/054string-equal.subx
@@ -14,14 +14,6 @@
     cd/syscall  0x80/imm8
 
 string-equal:  # s : string, benchmark : string -> EAX : boolean
-    # . prolog
-    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
     # pseudocode:
     #   if s->length != b->length return false
     #   for i = 0;  i < s->length;  ++i
@@ -34,6 +26,14 @@ string-equal:  # s : string, benchmark : string -> EAX : boolean
     #   b[i]: EBX
     #   s[i]: EAX
     #
+    # . prolog
+    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
     # var s/EAX : (address array byte)
     8b/copy                         1/mod/*+disp8   5/rm32/EBP    .           .             .           0/r32/EAX   8/disp8         .                 # copy *(EBP+8) to EAX
     # var benchmark/EBX : (address array byte)
diff --git a/subx/062write-byte.subx b/subx/062write-byte.subx
index ad29d9f1..2e348aa4 100644
--- a/subx/062write-byte.subx
+++ b/subx/062write-byte.subx
@@ -66,11 +66,11 @@ write-byte:  # f : (address buffered-file), n : int -> <void>
     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
 $write-byte:to-stream:
     # write to stream
-    # f->data[f->read] = LSB(n)
+    # f->data[f->write] = LSB(n)
     31/xor                          3/mod/direct    0/rm32/EAX    .           .             .           0/r32/EAX   .               .                 # clear EAX
     8a/copy-byte                    1/mod/*+disp8   5/rm32/EBP    .           .             .           0/r32/AL    0xc/disp8       .                 # copy byte at *(EBP+12) to AL
     88/copy-byte                    1/mod/*+disp8   4/rm32/sib    7/base/EDI  1/index/ECX   .           0/r32/AL    0x10/disp8      .                 # copy AL to *(EDI+ECX+16)
-    # ++f->read
+    # ++f->write
     ff          0/subop/increment   1/mod/*+disp8   7/rm32/EDI    .           .             .           .           4/disp8         .                 # increment *(EDI+4)
 $write-byte:end:
     # . restore registers
diff --git a/subx/066allocate.subx b/subx/066allocate.subx
index a4ea687c..37b01d21 100644
--- a/subx/066allocate.subx
+++ b/subx/066allocate.subx
@@ -183,6 +183,12 @@ allocate-region:  # ad : (address allocation-descriptor), n : int -> new-ad : (a
     5d/pop-to-EBP
     c3/return
 
+# We could create a more general '$abort' jump target, but then we'd need to do
+# a conditional jump followed by loading the error message and an unconditional
+# jump. Or we'd need to unconditionally load the error message before a
+# conditional jump, even if it's unused the vast majority of the time. This way
+# we bloat a potentially cold segment in RAM so we can abort with a single
+# instruction.
 $allocate-region:abort:
     # . _write(2/stderr, error)
     # . . push args
diff --git a/subx/068read-line.subx b/subx/068read-line.subx
new file mode 100644
index 00000000..5e35ce3c
--- /dev/null
+++ b/subx/068read-line.subx
@@ -0,0 +1,198 @@
+== 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
+
+# main:
+    e8/call  run-tests/disp32  # 'run-tests' is a function created automatically by SubX. It calls all functions that start with 'test-'.
+    # syscall(exit, Num-test-failures)
+    8b/copy                         0/mod/indirect  5/rm32/.disp32            .             .           3/r32/EBX   Num-test-failures/disp32          # copy *Num-test-failures to EBX
+    b8/copy-to-EAX  1/imm32/exit
+    cd/syscall  0x80/imm8
+
+# read bytes from 'f' until (and including) a newline and store them into 's'
+# return true if no data found, false otherwise
+# just abort if 's' is too small
+read-line:  # f : (address buffered-file), s : (address stream byte) -> eof?/EAX
+    # pseudocode:
+    #   loop:
+    #     if (s->write >= s->length) abort
+    #     if (f->read >= f->write) populate stream from file
+    #     if (f->write == 0) break
+    #     AL = f->data[f->read]
+    #     s->data[s->write] = AL
+    #     ++f->read
+    #     ++s->write
+    #     if AL == '\n' break
+    # . prolog
+    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
+    # ECX = f->read
+    8b/copy                         1/mod/*+disp8   6/rm32/ESI    .           .             .           1/r32/ECX   8/disp8         .                 # copy *(ESI+8) to ECX
+    # EDI = s
+    8b/copy                         1/mod/*+disp8   5/rm32/EBP    .           .             .           7/r32/EDI   0xc/disp8       .                 # copy *(EBP+12) to EDI
+    # EDX = s->write
+    8b/copy                         0/mod/indirect  7/rm32/EDI    .           .             .           2/r32/EDX   .               .                 # copy *EDI to EDX
+$read-line:loop:
+    # if (s->write >= s->length) abort
+    3b/compare                      1/mod/*+disp8   7/rm32/EDI    .           .             .           2/r32/EDX   8/disp8         .                 # compare EDX with *(EDI+8)
+    7d/jump-if-greater-or-equal  $read-line:abort/disp8
+    # if (f->read >= f->write) populate stream from file
+    3b/compare                      1/mod/*+disp8   6/rm32/ESI    .           .             .           1/r32/ECX   4/disp8         .                 # compare ECX with *(ESI+4)
+    7c/jump-if-lesser  $read-line:from-stream/disp8
+    # . clear-stream(stream = f+4)
+    # . . push args
+    8d/copy-address                 1/mod/*+disp8   6/rm32/ESI    .           .             .           0/r32/EAX   4/disp8         .                 # copy ESI+4 to EAX
+    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
+    # . f->read must now be 0; update ECX
+    31/xor                          3/mod/direct    1/rm32/ECX    .           .             .           1/r32/ECX   .               .                 # clear ECX
+    # . EAX = read(f->fd, stream = f+4)
+    # . . push args
+    50/push-EAX
+    ff          6/subop/push        0/mod/indirect  6/rm32/ESI    .           .             .           .           .               .                 # push *ESI
+    # . . call
+    e8/call  read/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
+    # if f->write == 0 return true
+    # . if EAX == 0 return true
+    81          7/subop/compare     3/mod/direct    0/rm32/EAX    .           .             .           .           .               0/imm32           # compare EAX
+    75/jump-if-not-equal  $read-line:from-stream/disp8
+    b8/copy-to-EAX  0xffffffff/imm32
+    eb/jump  $read-line:end/disp8
+$read-line:from-stream:
+    # AL = f->data[f->read]
+    31/xor                          3/mod/direct    0/rm32/EAX    .           .             .           0/r32/EAX   .               .                 # clear EAX
+    8a/copy-byte                    1/mod/*+disp8   4/rm32/sib    6/base/ESI  1/index/ECX   .           0/r32/AL    0x10/disp8      .                 # copy byte at *(ESI+ECX+16) to AL
+    # s->data[s->write] = AL
+    88/copy-byte                    1/mod/*+disp8   4/rm32/sib    7/base/EDI  2/index/EDX   .           0/r32/AL    0xc/disp8       .                 # copy AL to *(EDI+EDX+12)
+    # ++f->read
+    41/increment-ECX
+    # ++s->write
+    42/increment-EDX
+    # if AL == '\n' return false
+    81          7/subop/compare     3/mod/direct    0/rm32/EAX    .           .             .           .           .               0xa/imm32         # compare EAX
+    75/jump-if-not-equal  $read-line:loop/disp8
+    31/xor                          3/mod/direct    0/rm32/EAX    .           .             .           0/r32/EAX   .               .                 # clear EAX
+$read-line:end:
+    # save f->read
+    89/copy                         1/mod/*+disp8   6/rm32/ESI    .           .             .           1/r32/ECX   8/disp8         .                 # copy ECX to *(ESI+8)
+    # save s->write
+    89/copy                         0/mod/indirect  7/rm32/EDI    .           .             .           2/r32/EDX   .               .                 # copy EDX to *EDI
+    # . restore registers
+    5f/pop-to-EDI
+    5e/pop-to-ESI
+    5a/pop-to-EDX
+    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
+
+$read-line:abort:
+    # . _write(2/stderr, error)
+    # . . push args
+    68/push  "read-line: line too long"/imm32
+    68/push  2/imm32/stderr
+    # . . call
+    e8/call  _write/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
+    # . syscall(exit, 1)
+    bb/copy-to-EBX  1/imm32
+    b8/copy-to-EAX  1/imm32/exit
+    cd/syscall  0x80/imm8
+    # never gets here
+
+test-read-line:
+    # - check that read-line stops at a newline
+    # 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
+    # . 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
+    # write(_test-stream, "ab\ncd")
+    # . 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
+    # . write(_test-stream, "\n")
+    # . . push args
+    68/push Newline/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, "cd")
+    # . . push args
+    68/push  "cd"/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
+    # read a line from _test-stream (buffered by _test-buffered-file) into _test-stream-buffer
+    # . EAX = read-line(_test-buffered-file, _test-stream-buffer)
+    # . . push args
+    68/push  _test-stream-buffer/imm32
+    68/push  _test-buffered-file/imm32
+    # . . call
+    e8/call  read-line/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
+    # check-ints-equal(EAX, 0/not-at-eof, msg)
+    # . . push args
+    68/push  "F - test-read-line: return value"/imm32
+    68/push  0/imm32/not-at-eof
+    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-ints-equal(*_test-stream-buffer->data, 61/a 62/b 0a/newline 00, msg)
+    # . . push args
+    68/push  "F - test-read-line"/imm32
+    68/push  0x000a6261/imm32
+    # . . push *_test-stream->data
+    b8/copy-to-EAX  _test-stream-buffer/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-read-line-returns-true-on-eof:
+#? 
+#? test-read-line-reads-final-line-until-eof:
+
+# . . vim:nowrap:textwidth=0
diff --git a/subx/apps/crenshaw2-1 b/subx/apps/crenshaw2-1
index efb462ec..20ac912a 100755
--- a/subx/apps/crenshaw2-1
+++ b/subx/apps/crenshaw2-1
Binary files differdiff --git a/subx/apps/crenshaw2-1b b/subx/apps/crenshaw2-1b
index e6dceafa..37145d9c 100755
--- a/subx/apps/crenshaw2-1b
+++ b/subx/apps/crenshaw2-1b
Binary files differdiff --git a/subx/apps/factorial b/subx/apps/factorial
index ac02aca4..c05e588f 100755
--- a/subx/apps/factorial
+++ b/subx/apps/factorial
Binary files differdiff --git a/subx/apps/handle b/subx/apps/handle
index 17cdcc8f..d6d0a7f5 100755
--- a/subx/apps/handle
+++ b/subx/apps/handle
Binary files differdiff --git a/subx/apps/hex b/subx/apps/hex
index 8680176c..932a3ceb 100755
--- a/subx/apps/hex
+++ b/subx/apps/hex
Binary files differdiff --git a/subx/apps/pack.subx b/subx/apps/pack.subx
index da9fe66f..1cf57867 100644
--- a/subx/apps/pack.subx
+++ b/subx/apps/pack.subx
@@ -122,7 +122,6 @@ $main:end:
 
 # helpers:
 #   new-stream(length int, elemsize int) -- allocate length*elemsize bytes, initialize first word with length*elemsize
-#   clear-stream(array) -- skip length, clear length bytes after
 #   read-line(in : &buffered-file, line : stream byte, err : &buffered-file, ed : &exit-descriptor)
 #   next-word(line : stream byte, out : &slice)
 #     responsible for skipping whitespace and comments