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-rwxr-xr-xsubx/apps/factorialbin0 -> 156 bytes
-rw-r--r--subx/apps/factorial.subx64
-rwxr-xr-xsubx/examples/ex7bin156 -> 313 bytes
-rw-r--r--subx/examples/ex7.subx139
-rwxr-xr-xsubx/examples/ex8bin313 -> 144 bytes
-rw-r--r--subx/examples/ex8.subx140
-rwxr-xr-xsubx/examples/ex9bin144 -> 0 bytes
-rw-r--r--subx/examples/ex9.subx61
-rwxr-xr-xsubx/gen8
-rwxr-xr-xsubx/run8
-rwxr-xr-xsubx/test_layers2
11 files changed, 217 insertions, 205 deletions
diff --git a/subx/apps/factorial b/subx/apps/factorial
new file mode 100755
index 00000000..daea2cf4
--- /dev/null
+++ b/subx/apps/factorial
Binary files differdiff --git a/subx/apps/factorial.subx b/subx/apps/factorial.subx
new file mode 100644
index 00000000..de9953bf
--- /dev/null
+++ b/subx/apps/factorial.subx
@@ -0,0 +1,64 @@
+## compute the factorial of 5, and return the result in the exit code
+#
+# To run:
+#   $ subx translate apps/factorial.subx apps/factorial
+#   $ subx run apps/factorial
+# Expected result:
+#   $ echo $?
+#   120
+
+== 0x08048054  # code segment, after leaving room for ELF header
+# instruction                     effective address                                                   operand     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:
+  # prepare to make a call
+  55/push                         .               .             .           .             .           .           .               .                 # push EBP
+  89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
+  # factorial(5)
+  68/push                         .               .             .           .             .           .           .               5/imm32           # push 5
+  e8/call                         .               .             .           .             .           .           factorial/disp32
+  # discard arg
+  5a/pop                          .               .             .           .             .           .           .               .                 # pop into EDX
+  # clean up after call
+  89/copy                         3/mod/direct    4/rm32/ESP    .           .             .           5/r32/EBP   .               .                 # copy EBP to ESP
+  5d/pop                          .               .             .           .             .           .           .               .                 # pop to EBP
+
+  # exit(EAX)
+  89/copy                         3/mod/direct    3/rm32/EBX    .           .             .           0/r32/EAX   .               .                 # copy EAX to EBX
+  b8/copy                         .               .             .           .             .           .           .               1/imm32           # copy 1 to EAX
+  cd/syscall                      .               .             .           .             .           .           .               0x80/imm8         # int 80h
+
+# factorial(n)
+factorial:
+  # initialize n
+  8b/copy                         1/mod/*+disp8   4/rm32/sib    4/base/ESP  4/index/none              2/r32/EDX   4/disp8         .                 # copy *(ESP+4) to EDX
+  # initialize EAX to 1 (base case)
+  b8/copy                         .               .             .           .             .           .           .               1/imm32           # copy 1 to EAX
+  # if (n <= 1) jump exit
+  81          7/subop/compare     3/mod/direct    2/rm32/EDX    .           .             .           .           .               1/imm32           # compare EDX with 1
+  7e/jump-if-<=                   .               .             .           .             .           .           $factorial:exit/disp8             # jump if <= to $factorial:exit
+  # EBX: n-1
+  89/copy                         3/mod/direct    3/rm32/EBX    .           .             .           2/r32/EDX   .               .                 # copy EDX to EBX
+  81          5/subop/subtract    3/mod/direct    3/rm32/EBX    .           .             .           .           .               1/imm32           # subtract 1 from EBX
+  # prepare call
+  55/push                         .               .             .           .             .           .           .               .                 # push EBP
+  89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
+  # EAX: factorial(n-1)
+  53/push                         .               .             .           .             .           .           .               .                 # push EBX
+  e8/call                         .               .             .           .             .           .           factorial/disp32
+  # discard arg
+  5e/pop                          .               .             .           .             .           .           .               .                 # pop into ESI
+  # clean up after call
+  89/copy                         3/mod/direct    4/rm32/ESP    .           .             .           5/r32/EBP   .               .                 # copy EBP to ESP
+  5d/pop                          .               .             .           .             .           .           .               .                 # pop to EBP
+  # refresh n
+  8b/copy                         1/mod/*+disp8   4/rm32/sib    4/base/ESP  4/index/none              2/r32/EDX   4/disp8         .                 # copy *(ESP+4) to EDX
+  # return n * factorial(n-1)
+  0f af/multiply                  3/mod/direct    2/rm32/EDX    .           .             .           0/r32/EAX   .               .                 # multiply EDX (n) into EAX (factorial(n-1))
+  # TODO: check for overflow
+$factorial:exit:
+  c3/return
+
+# vim:ft=subx:nowrap:so=0
diff --git a/subx/examples/ex7 b/subx/examples/ex7
index daea2cf4..d756271e 100755
--- a/subx/examples/ex7
+++ b/subx/examples/ex7
Binary files differdiff --git a/subx/examples/ex7.subx b/subx/examples/ex7.subx
index 86e018c8..6f8d3979 100644
--- a/subx/examples/ex7.subx
+++ b/subx/examples/ex7.subx
@@ -1,64 +1,99 @@
-## compute the factorial of 5, and return the result in the exit code
+## example showing file syscalls
+# Create a file, open it for writing, write a character to it, close it, open
+# it for reading, read a character from it, close it, delete it, and return
+# the character read.
 #
 # To run:
-#   $ subx translate ex7.subx ex7
-#   $ subx run ex7
+#   $ subx translate ex8.subx ex8
+#   $ subx run ex8
 # Expected result:
 #   $ echo $?
-#   120
+#   97
 
-== 0x08048054  # code segment, after leaving room for ELF header
+== 0x08048074  # code segment, after leaving room for ELF header and segment headers
 # instruction                     effective address                                                   operand     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:
-  # prepare to make a call
-  55/push                         .               .             .           .             .           .           .               .                 # push EBP
-  89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
-  # factorial(5)
-  68/push                         .               .             .           .             .           .           .               5/imm32           # push 5
-  e8/call                         .               .             .           .             .           .           factorial/disp32
-  # discard arg
-  5a/pop                          .               .             .           .             .           .           .               .                 # pop into EDX
-  # clean up after call
-  89/copy                         3/mod/direct    4/rm32/ESP    .           .             .           5/r32/EBP   .               .                 # copy EBP to ESP
-  5d/pop                          .               .             .           .             .           .           .               .                 # pop to EBP
+  ## creat(filename)
+  bb/copy                         .               .             .           .             .           .           .               0x08049131/imm32/fname  # copy to EBX
+  b9/copy                         .               .             .           .             .           .           .               0x180/imm32/fixed-perms # copy 0 to ECX
+  b8/copy                         .               .             .           .             .           .           .               8/imm32/creat           # copy 8 to EAX
+  cd/syscall                      .               .             .           .             .           .           .               0x80/imm8               # int 80h
 
-  # exit(EAX)
-  89/copy                         3/mod/direct    3/rm32/EBX    .           .             .           0/r32/EAX   .               .                 # copy EAX to EBX
-  b8/copy                         .               .             .           .             .           .           .               1/imm32           # copy 1 to EAX
-  cd/syscall                      .               .             .           .             .           .           .               0x80/imm8         # int 80h
+  ## fd = open(filename, O_WRONLY, 0)
+  bb/copy                         .               .             .           .             .           .           .               0x08049131/imm32/fname  # copy to EBX
+  b9/copy                         .               .             .           .             .           .           .               1/imm32/wronly          # copy 1 to ECX
+  ba/copy                         .               .             .           .             .           .           .               0x180/imm32/fixed-perms # copy 0 to EDX
+  b8/copy                         .               .             .           .             .           .           .               5/imm32/open            # copy 5 to EAX
+  cd/syscall                      .               .             .           .             .           .           .               0x80/imm8               # int 80h
+  # save fd
+  bb/copy                         .               .             .           .             .           .           .               0x08049125/imm32/fd     # copy to EBX
+  89/copy                         0/mod/indirect  3/rm32/EBX                                          0/r32/EAX                                           # copy EAX to *EBX
 
-# factorial(n)
-factorial:
-  # initialize n
-  8b/copy                         1/mod/*+disp8   4/rm32/sib    4/base/ESP  4/index/none              2/r32/EDX   4/disp8         .                 # copy *(ESP+4) to EDX
-  # initialize EAX to 1 (base case)
-  b8/copy                         .               .             .           .             .           .           .               1/imm32           # copy 1 to EAX
-  # if (n <= 1) jump exit
-  81          7/subop/compare     3/mod/direct    2/rm32/EDX    .           .             .           .           .               1/imm32           # compare EDX with 1
-  7e/jump-if-<=                   .               .             .           .             .           .           $factorial:exit/disp8             # jump if <= to $factorial:exit
-  # EBX: n-1
-  89/copy                         3/mod/direct    3/rm32/EBX    .           .             .           2/r32/EDX   .               .                 # copy EDX to EBX
-  81          5/subop/subtract    3/mod/direct    3/rm32/EBX    .           .             .           .           .               1/imm32           # subtract 1 from EBX
-  # prepare call
-  55/push                         .               .             .           .             .           .           .               .                 # push EBP
-  89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
-  # EAX: factorial(n-1)
-  53/push                         .               .             .           .             .           .           .               .                 # push EBX
-  e8/call                         .               .             .           .             .           .           factorial/disp32
-  # discard arg
-  5e/pop                          .               .             .           .             .           .           .               .                 # pop into ESI
-  # clean up after call
-  89/copy                         3/mod/direct    4/rm32/ESP    .           .             .           5/r32/EBP   .               .                 # copy EBP to ESP
-  5d/pop                          .               .             .           .             .           .           .               .                 # pop to EBP
-  # refresh n
-  8b/copy                         1/mod/*+disp8   4/rm32/sib    4/base/ESP  4/index/none              2/r32/EDX   4/disp8         .                 # copy *(ESP+4) to EDX
-  # return n * factorial(n-1)
-  0f af/multiply                  3/mod/direct    2/rm32/EDX    .           .             .           0/r32/EAX   .               .                 # multiply EDX (n) into EAX (factorial(n-1))
-  # TODO: check for overflow
-$factorial:exit:
-  c3/return
+  ## write(fd, "a", 1)
+  # load fd
+  bb/copy                         .               .             .           .             .           .           .               0x08049125/imm32/fd     # copy to EBX
+  8b/copy                         0/mod/indirect  3/rm32/EBX                                          3/r32/EBX                                           # copy *EBX to EBX
+  #
+  b9/copy                         .               .             .           .             .           .           .               0x08049129/imm32/a      # copy to ECX
+  ba/copy                         .               .             .           .             .           .           .               1/imm32/size            # copy 1 to EDX
+  b8/copy                         .               .             .           .             .           .           .               4/imm32/write           # copy 4 to EAX
+  cd/syscall                      .               .             .           .             .           .           .               0x80/imm8               # int 80h
 
-# vim:ft=subx:nowrap:so=0
+  ## close(fd)
+  # load fd
+  bb/copy                         .               .             .           .             .           .           .               0x08049125/imm32/fd     # copy to EBX
+  8b/copy                         0/mod/indirect  3/rm32/EBX                                          3/r32/EBX                                           # copy *EBX to EBX
+  #
+  b8/copy                         .               .             .           .             .           .           .               6/imm32/close           # copy 6 to EAX
+  cd/syscall                      .               .             .           .             .           .           .               0x80/imm8               # int 80h
+
+  ## fd = open(filename, O_RDONLY, 0)
+  bb/copy                         .               .             .           .             .           .           .               0x08049131/imm32/fname  # copy to EBX
+  b9/copy                         .               .             .           .             .           .           .               0/imm32/rdonly          # copy 0 to ECX
+  ba/copy                         .               .             .           .             .           .           .               0x180/imm32/fixed-perms # copy 0 to EDX
+  b8/copy                         .               .             .           .             .           .           .               5/imm32/open            # copy 5 to EAX
+  cd/syscall                      .               .             .           .             .           .           .               0x80/imm8               # int 80h
+  # save fd
+  bb/copy                         .               .             .           .             .           .           .               0x08049125/imm32/fd     # copy to EBX
+  89/copy                         0/mod/indirect  3/rm32/EBX                                          0/r32/EAX                                           # copy EAX to *EBX
+
+  ## read(fd, b, 1)
+  # load fd
+  bb/copy                         .               .             .           .             .           .           .               0x08049125/imm32/fd     # copy to EBX
+  8b/copy                         0/mod/indirect  3/rm32/EBX                                          3/r32/EBX                                           # copy *EBX to EBX
+  #
+  b9/copy                         .               .             .           .             .           .           .               0x0804912d/imm32/b      # copy to ECX
+  ba/copy                         .               .             .           .             .           .           .               1/imm32/size            # copy 1 to EDX
+  b8/copy                         .               .             .           .             .           .           .               3/imm32/read            # copy 3 to EAX
+  cd/syscall                      .               .             .           .             .           .           .               0x80/imm8               # int 80h
+
+  ## close(fd)
+  # load fd
+  bb/copy                         .               .             .           .             .           .           .               0x08049125/imm32/fd     # copy to EBX
+  8b/copy                         0/mod/indirect  3/rm32/EBX                                          3/r32/EBX                                           # copy *EBX to EBX
+  #
+  b8/copy                         .               .             .           .             .           .           .               6/imm32/close           # copy 8 to EAX
+  cd/syscall                      .               .             .           .             .           .           .               0x80/imm8               # int 80h
+
+  ## unlink(filename)
+  bb/copy                         .               .             .           .             .           .           .               0x08049131/imm32/fname  # copy to EBX
+  b8/copy                         .               .             .           .             .           .           .               0xa/imm32/unlink        # copy 8 to EAX
+  cd/syscall                      .               .             .           .             .           .           .               0x80/imm8               # int 80h
+
+  ## exit(b)
+  # load b
+  bb/copy                         .               .             .           .             .           .           .               0x0804912d/imm32/b      # copy to EBX
+  8b/copy                         0/mod/indirect  3/rm32/EBX                                          3/r32/EBX                                           # copy *EBX to EBX
+  #
+  b8/copy                         .               .             .           .             .           .           .               1/imm32/exit            # copy 1 to EAX
+  cd/syscall                      .               .             .           .             .           .           .               0x80/imm8               # int 80h
+
+== 0x08049125  # data segment
+00 00 00 00  # fd
+61 00 00 00  # a: string to write to file: 'a'
+00 00 00 00  # b: space for string read from file
+2e 66 6f 6f 00 00 00 00  # filename: '.foo'
+
+# vim:ft=subx:nowrap:tw&
diff --git a/subx/examples/ex8 b/subx/examples/ex8
index d756271e..47c79e3c 100755
--- a/subx/examples/ex8
+++ b/subx/examples/ex8
Binary files differdiff --git a/subx/examples/ex8.subx b/subx/examples/ex8.subx
index 6f8d3979..9ea547f1 100644
--- a/subx/examples/ex8.subx
+++ b/subx/examples/ex8.subx
@@ -1,99 +1,61 @@
-## example showing file syscalls
-# Create a file, open it for writing, write a character to it, close it, open
-# it for reading, read a character from it, close it, delete it, and return
-# the character read.
+# Example reading commandline arguments: compute length of first arg.
 #
 # To run:
-#   $ subx translate ex8.subx ex8
-#   $ subx run ex8
+#   $ subx translate ex9.subx ex9
+#   $ subx run ex9 abc de fghi
 # Expected result:
 #   $ echo $?
-#   97
-
-== 0x08048074  # code segment, after leaving room for ELF header and segment headers
+#   3  # length of 'abc'
+#
+# At the start of a SubX program:
+#   argc: *ESP
+#   argv[0]: *(ESP+4)
+#   argv[1]: *(ESP+8)
+#   ...
+# Locals start from ESP-4 downwards.
+
+== 0x08048054  # code segment, after leaving room for ELF header and segment headers
 # instruction                     effective address                                                   operand     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
-
-  ## creat(filename)
-  bb/copy                         .               .             .           .             .           .           .               0x08049131/imm32/fname  # copy to EBX
-  b9/copy                         .               .             .           .             .           .           .               0x180/imm32/fixed-perms # copy 0 to ECX
-  b8/copy                         .               .             .           .             .           .           .               8/imm32/creat           # copy 8 to EAX
-  cd/syscall                      .               .             .           .             .           .           .               0x80/imm8               # int 80h
-
-  ## fd = open(filename, O_WRONLY, 0)
-  bb/copy                         .               .             .           .             .           .           .               0x08049131/imm32/fname  # copy to EBX
-  b9/copy                         .               .             .           .             .           .           .               1/imm32/wronly          # copy 1 to ECX
-  ba/copy                         .               .             .           .             .           .           .               0x180/imm32/fixed-perms # copy 0 to EDX
-  b8/copy                         .               .             .           .             .           .           .               5/imm32/open            # copy 5 to EAX
-  cd/syscall                      .               .             .           .             .           .           .               0x80/imm8               # int 80h
-  # save fd
-  bb/copy                         .               .             .           .             .           .           .               0x08049125/imm32/fd     # copy to EBX
-  89/copy                         0/mod/indirect  3/rm32/EBX                                          0/r32/EAX                                           # copy EAX to *EBX
-
-  ## write(fd, "a", 1)
-  # load fd
-  bb/copy                         .               .             .           .             .           .           .               0x08049125/imm32/fd     # copy to EBX
-  8b/copy                         0/mod/indirect  3/rm32/EBX                                          3/r32/EBX                                           # copy *EBX to EBX
-  #
-  b9/copy                         .               .             .           .             .           .           .               0x08049129/imm32/a      # copy to ECX
-  ba/copy                         .               .             .           .             .           .           .               1/imm32/size            # copy 1 to EDX
-  b8/copy                         .               .             .           .             .           .           .               4/imm32/write           # copy 4 to EAX
-  cd/syscall                      .               .             .           .             .           .           .               0x80/imm8               # int 80h
-
-  ## close(fd)
-  # load fd
-  bb/copy                         .               .             .           .             .           .           .               0x08049125/imm32/fd     # copy to EBX
-  8b/copy                         0/mod/indirect  3/rm32/EBX                                          3/r32/EBX                                           # copy *EBX to EBX
-  #
-  b8/copy                         .               .             .           .             .           .           .               6/imm32/close           # copy 6 to EAX
-  cd/syscall                      .               .             .           .             .           .           .               0x80/imm8               # int 80h
-
-  ## fd = open(filename, O_RDONLY, 0)
-  bb/copy                         .               .             .           .             .           .           .               0x08049131/imm32/fname  # copy to EBX
-  b9/copy                         .               .             .           .             .           .           .               0/imm32/rdonly          # copy 0 to ECX
-  ba/copy                         .               .             .           .             .           .           .               0x180/imm32/fixed-perms # copy 0 to EDX
-  b8/copy                         .               .             .           .             .           .           .               5/imm32/open            # copy 5 to EAX
-  cd/syscall                      .               .             .           .             .           .           .               0x80/imm8               # int 80h
-  # save fd
-  bb/copy                         .               .             .           .             .           .           .               0x08049125/imm32/fd     # copy to EBX
-  89/copy                         0/mod/indirect  3/rm32/EBX                                          0/r32/EAX                                           # copy EAX to *EBX
-
-  ## read(fd, b, 1)
-  # load fd
-  bb/copy                         .               .             .           .             .           .           .               0x08049125/imm32/fd     # copy to EBX
-  8b/copy                         0/mod/indirect  3/rm32/EBX                                          3/r32/EBX                                           # copy *EBX to EBX
-  #
-  b9/copy                         .               .             .           .             .           .           .               0x0804912d/imm32/b      # copy to ECX
-  ba/copy                         .               .             .           .             .           .           .               1/imm32/size            # copy 1 to EDX
-  b8/copy                         .               .             .           .             .           .           .               3/imm32/read            # copy 3 to EAX
-  cd/syscall                      .               .             .           .             .           .           .               0x80/imm8               # int 80h
-
-  ## close(fd)
-  # load fd
-  bb/copy                         .               .             .           .             .           .           .               0x08049125/imm32/fd     # copy to EBX
-  8b/copy                         0/mod/indirect  3/rm32/EBX                                          3/r32/EBX                                           # copy *EBX to EBX
-  #
-  b8/copy                         .               .             .           .             .           .           .               6/imm32/close           # copy 8 to EAX
-  cd/syscall                      .               .             .           .             .           .           .               0x80/imm8               # int 80h
-
-  ## unlink(filename)
-  bb/copy                         .               .             .           .             .           .           .               0x08049131/imm32/fname  # copy to EBX
-  b8/copy                         .               .             .           .             .           .           .               0xa/imm32/unlink        # copy 8 to EAX
-  cd/syscall                      .               .             .           .             .           .           .               0x80/imm8               # int 80h
-
-  ## exit(b)
-  # load b
-  bb/copy                         .               .             .           .             .           .           .               0x0804912d/imm32/b      # copy to EBX
-  8b/copy                         0/mod/indirect  3/rm32/EBX                                          3/r32/EBX                                           # copy *EBX to EBX
-  #
+  # var s = argv[1] (EBX)
+  8b/copy                         1/mod/*+disp8   4/rm32/sib    4/base/ESP  4/index/none              3/r32/EBX   8/disp8         .                       # copy *(ESP+8) to EBX
+  # call ascii_length(EBX)
+    # prepare call
+  55/push                         .               .             .           .             .           .           .               .                       # push EBP
+  89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                       # copy ESP to EBP
+    # push args
+  53/push                         .               .             .           .             .           .           .               .                       # push EBX
+    # call
+  e8/call                         .               .             .           .             .           .           ascii_length/disp32
+    # discard args
+  5a/pop                          .               .             .           .             .           .           .               .                       # pop into EDX
+    # clean up after call
+  89/copy                         3/mod/direct    4/rm32/ESP    .           .             .           5/r32/EBP   .               .                       # copy EBP to ESP
+  5d/pop                          .               .             .           .             .           .           .               .                       # pop to EBP
+
+  # exit(EAX)
+  89/copy                         3/mod/direct    3/rm32/EBX    .           .             .           0/r32/EAX   .               .                       # copy EAX to EBX
   b8/copy                         .               .             .           .             .           .           .               1/imm32/exit            # copy 1 to EAX
   cd/syscall                      .               .             .           .             .           .           .               0x80/imm8               # int 80h
 
-== 0x08049125  # data segment
-00 00 00 00  # fd
-61 00 00 00  # a: string to write to file: 'a'
-00 00 00 00  # b: space for string read from file
-2e 66 6f 6f 00 00 00 00  # filename: '.foo'
-
-# vim:ft=subx:nowrap:tw&
+ascii_length:  # (s)
+  # initialize s (EDX)
+  8b/copy                         1/mod/*+disp8   4/rm32/sib    4/base/ESP  4/index/none              2/r32/EDX   4/disp8                                 # copy *(ESP+4) to EDX
+  # var result = 0 (EAX)
+  b8/copy                         .               .             .           .             .           .           .               0/imm32                 # copy 1 to EAX
+$al_loop:
+  # var c = *s (ECX)
+  8a/copy                         0/mod/*         2/rm32/EDX    .           .             .           1/r32/ECX   .               .                       # copy byte at *EDX to lower byte of ECX
+  # if c == '\0' break
+  81          7/subop/compare     3/mod/direct    1/rm32/ECX    .           .             .           .           .               0/imm32                 # compare ECX with 0
+  74/jump-if-zero                 .               .             .           .             .           .           .               $al_ret/disp8           # jump if equal
+  # ++s
+  81          0/subop/add         3/mod/direct    2/rm32/EDX    .           .             .           .           .               1/imm32                 # add 1 to EDX
+  # ++result
+  81          0/subop/add         3/mod/direct    0/rm32/EAX    .           .             .           .           .               1/imm32                 # add 1 to EAX
+  # loop
+  eb/jump                         .               .             .           .             .           .           .               $al_loop/disp8          # jump $al_loop
+$al_ret:
+  # return (result in EAX)
+  c3/return
diff --git a/subx/examples/ex9 b/subx/examples/ex9
deleted file mode 100755
index 47c79e3c..00000000
--- a/subx/examples/ex9
+++ /dev/null
Binary files differdiff --git a/subx/examples/ex9.subx b/subx/examples/ex9.subx
deleted file mode 100644
index 9ea547f1..00000000
--- a/subx/examples/ex9.subx
+++ /dev/null
@@ -1,61 +0,0 @@
-# Example reading commandline arguments: compute length of first arg.
-#
-# To run:
-#   $ subx translate ex9.subx ex9
-#   $ subx run ex9 abc de fghi
-# Expected result:
-#   $ echo $?
-#   3  # length of 'abc'
-#
-# At the start of a SubX program:
-#   argc: *ESP
-#   argv[0]: *(ESP+4)
-#   argv[1]: *(ESP+8)
-#   ...
-# Locals start from ESP-4 downwards.
-
-== 0x08048054  # code segment, after leaving room for ELF header and segment headers
-# instruction                     effective address                                                   operand     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
-  # var s = argv[1] (EBX)
-  8b/copy                         1/mod/*+disp8   4/rm32/sib    4/base/ESP  4/index/none              3/r32/EBX   8/disp8         .                       # copy *(ESP+8) to EBX
-  # call ascii_length(EBX)
-    # prepare call
-  55/push                         .               .             .           .             .           .           .               .                       # push EBP
-  89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                       # copy ESP to EBP
-    # push args
-  53/push                         .               .             .           .             .           .           .               .                       # push EBX
-    # call
-  e8/call                         .               .             .           .             .           .           ascii_length/disp32
-    # discard args
-  5a/pop                          .               .             .           .             .           .           .               .                       # pop into EDX
-    # clean up after call
-  89/copy                         3/mod/direct    4/rm32/ESP    .           .             .           5/r32/EBP   .               .                       # copy EBP to ESP
-  5d/pop                          .               .             .           .             .           .           .               .                       # pop to EBP
-
-  # exit(EAX)
-  89/copy                         3/mod/direct    3/rm32/EBX    .           .             .           0/r32/EAX   .               .                       # copy EAX to EBX
-  b8/copy                         .               .             .           .             .           .           .               1/imm32/exit            # copy 1 to EAX
-  cd/syscall                      .               .             .           .             .           .           .               0x80/imm8               # int 80h
-
-ascii_length:  # (s)
-  # initialize s (EDX)
-  8b/copy                         1/mod/*+disp8   4/rm32/sib    4/base/ESP  4/index/none              2/r32/EDX   4/disp8                                 # copy *(ESP+4) to EDX
-  # var result = 0 (EAX)
-  b8/copy                         .               .             .           .             .           .           .               0/imm32                 # copy 1 to EAX
-$al_loop:
-  # var c = *s (ECX)
-  8a/copy                         0/mod/*         2/rm32/EDX    .           .             .           1/r32/ECX   .               .                       # copy byte at *EDX to lower byte of ECX
-  # if c == '\0' break
-  81          7/subop/compare     3/mod/direct    1/rm32/ECX    .           .             .           .           .               0/imm32                 # compare ECX with 0
-  74/jump-if-zero                 .               .             .           .             .           .           .               $al_ret/disp8           # jump if equal
-  # ++s
-  81          0/subop/add         3/mod/direct    2/rm32/EDX    .           .             .           .           .               1/imm32                 # add 1 to EDX
-  # ++result
-  81          0/subop/add         3/mod/direct    0/rm32/EAX    .           .             .           .           .               1/imm32                 # add 1 to EAX
-  # loop
-  eb/jump                         .               .             .           .             .           .           .               $al_loop/disp8          # jump $al_loop
-$al_ret:
-  # return (result in EAX)
-  c3/return
diff --git a/subx/gen b/subx/gen
index c9c5c85d..464506b3 100755
--- a/subx/gen
+++ b/subx/gen
@@ -1,5 +1,11 @@
 #!/usr/bin/env zsh
 # Build a specific example.
 
-CFLAGS=-g subx translate $1.subx `echo $1 |sed 's/\..*//'`
+if [[ $1 == 'ex'* ]]
+then
+  CFLAGS=-g subx translate examples/$1.subx examples/`echo $1 |sed 's/\..*//'`
+  exit $?
+fi
+
+CFLAGS=-g subx translate apps/$1.subx apps/`echo $1 |sed 's/\..*//'`
 exit $?
diff --git a/subx/run b/subx/run
index 277ce6d6..b66cace0 100755
--- a/subx/run
+++ b/subx/run
@@ -7,5 +7,11 @@ then
   exit 1
 fi
 
-CFLAGS=-g subx run $*
+if [[ $1 == 'ex'* ]]
+then
+  CFLAGS=-g subx run examples/$1
+  exit $?
+fi
+
+CFLAGS=-g subx run apps/$*
 exit $?
diff --git a/subx/test_layers b/subx/test_layers
index 9ade9ee1..12867b21 100755
--- a/subx/test_layers
+++ b/subx/test_layers
@@ -11,7 +11,7 @@ do
 done
 
 ./clean top
-for f in examples/ex*.subx
+for f in examples/ex*.subx apps/*.subx
 do
   echo checking $f
   target=`echo $f |sed 's/\..*//'`