# Function calls in a single line.
#
# To run (on Linux):
#   $ ./ntranslate 0*.subx apps/subx-common.subx apps/calls.subx
#   $ mv a.elf apps/calls
#   $ chmod +x apps/calls
#
# Example 1:
#   $ echo '(foo %eax)'                         |  apps/calls
#   # . (foo %eax)                                      # output has comments
#   ff 6/subop/push %eax                                # push
#   e8/call foo/disp32                                  # call
#   81 0/subop/add %esp 4/imm32                         # undo push
#
# Example 2:
#   $ echo '(foo Var1 *(eax + 4) "blah")'       |  apps/calls
#   # . (foo Var1 *(eax + 4) "blah")
#   68/push "blah"/imm32
#   ff 6/subop/push *(eax + 4)                          # push args in..
#   68/push Var1/imm32                                  # ..reverse order
#   e8/call foo/disp32
#   81 0/subop/add %esp 4/imm32                         # undo pushes
#
# Calls always begin with '(' as the first non-whitespace on a line.

== code

Entry:  # run tests if necessary, convert stdin if not
    # . prolog
    89/<- %ebp 4/r32/esp

    # initialize heap
    # . Heap = new-segment(Heap-size)
    # . . push args
    68/push Heap/imm32
    ff 6/subop/push *Heap-size
    # . . call
    e8/call new-segment/disp32
    # . . discard args
    81 0/subop/add %esp 8/imm32

    # - if argc > 1 and argv[1] == "test", then return run_tests()
    # if (argc <= 1) goto run-main
    81 7/subop/compare *ebp 1/imm32
    7e/jump-if-lesser-or-equal $run-main/disp8
    # if (!kernel-string-equal?(argv[1], "test")) goto run-main
    # . eax = kernel-string-equal?(argv[1], "test")
    # . . push args
    68/push "test"/imm32
    ff 6/subop/push *(ebp+8)
    # . . call
    e8/call kernel-string-equal?/disp32
    # . . discard args
    81 0/subop/add %esp 8/imm32
    # . if (eax == 0) goto run-main
    3d/compare-eax-and 0/imm32
    74/jump-if-equal $run-main/disp8
    # run-tests()
    e8/call run-tests/disp32
    # syscall(exit, *Num-test-failures)
    8b/-> *Num-test-failures 3/r32/ebx
    eb/jump $main:end/disp8
$run-main:
    # - otherwise convert stdin
    # convert(Stdin, Stdout)
    # . . push args
    68/push Stdout/imm32
    68/push Stdin/imm32
    # . . call
    e8/call convert/disp32
    # . . discard args
    81 0/subop/add %esp 8/imm32
    # syscall(exit, 0)
    bb/copy-to-ebx 0/imm32
$main:end:
    b8/copy-to-eax 1/imm32/exit
    cd/syscall 0x80/imm8

convert:  # in : (address buffered-file), out : (address buffered-file) -> <void>
    # pseudocode:
    #   var line = new-stream(512, 1)
    #   var words : (address stream slice) = new-stream(16, 8)  # at most function name and 15 args
    #   while true
    #     clear-stream(line)
    #     read-line-buffered(in, line)
    #     if (line->write == 0) break                           # end of file
    #     skip-chars-matching-whitespace(line)
    #     if line->data[line->read] != '('
    #       write-stream-data(out, line)
    #       continue
    #     # emit comment
    #     write-buffered(out, "# . ")
    #     write-stream-data(out, line)
    #     # emit code
    #     ++line->read  # skip '('
    #     clear-stream(words)
    #     words = parse-line(line)
    #     emit-call(out, words)
    #   flush(out)
    #
    # . prolog
    55/push-ebp
    89/<- %ebp 4/r32/esp
    # . save registers
    # var line/ecx : (address stream byte) = stream(512)
    81 5/subop/subtract %esp 0x200/imm32
    68/push 0x200/imm32/length
    68/push 0/imm32/read
    68/push 0/imm32/write
    89/<- %ecx 4/r32/esp
    # var words/edx : (address stream slice) = stream(16, 8)
    81 5/subop/subtract %esp 0x80/imm32
    68/push 0x80/imm32/length
    68/push 0/imm32/read
    68/push 0/imm32/write
    89/<- %edx 4/r32/esp
$convert:loop:
    # clear-stream(line)
    # . . push args
    51/push-ecx
    # . . call
    e8/call clear-stream/disp32
    # . . discard args
    81 0/subop/add %esp 4/imm32
    # read-line-buffered(in, line)
    # . . push args
    51/push-ecx
    ff 6/subop/push *(ebp+8)
    # . . call
    e8/call read-line-buffered/disp32
    # . . discard args
    81 0/subop/add %esp 8/imm32
$convert:check0:
    # if (line->write == 0) break
    81 7/subop/compare *ecx 0/imm32
    0f 84/jump-if-equal $convert:break/disp32
    # TODO
    e9/jump $convert:loop/disp32
$convert:break:
    # flush(out)
    # . . push args
    ff 6/subop/push *(ebp+0xc)
    # . . call
    e8/call flush/disp32
    # . . discard args
    81 0/subop/add %esp 4/imm32
$convert:end:
    # . reclaim locals
    81 0/subop/add %esp 0x298/imm32  # 0x20c + 0x8c
    # . restore registers
    # . epilog
    89/<- %esp 5/r32/ebp
    5d/pop-to-ebp
    c3/return

parse-line:  # line : (address stream byte), words : (address stream slice)
    # pseudocode:
    #   var word-slice : (address slice)
    #   while true
    #     word-slice = next-word-string-or-expression-without-metadata(line)
    #     if slice-empty?(word-slice)
    #       break                                 # end of line
    #     write-int(words, word-slice->start)
    #     write-int(words, word-slice->end)
    #
    # . prolog
    55/push-ebp
    89/<- %ebp 4/r32/esp
    # . save registers
$parse-line:end:
    # . reclaim locals
    # . restore registers
    # . epilog
    89/<- %esp 5/r32/ebp
    5d/pop-to-ebp
    c3/return

emit-call:  # out : (address buffered-file), words : (address stream slice)
    # pseudocode:
    #   if (words->write < 8) abort
    #   curr = &words->data[words->write-8]
    #   min = words->data
    #   # emit pushes
    #   while true
    #     if (curr <= min) break
    #     if *curr in '%' '*'
    #       write-buffered(out, "ff 6/subop/push ")
    #       write-slice-buffered(out, curr)
    #       write-buffered(out, "/imm32\n")
    #     else
    #       write-buffered(out, "68/push ")
    #       write-slice-buffered(out, curr)
    #       write-buffered(out, "/imm32\n")
    #     curr -= 8
    #   # emit call
    #   write-buffered(out, "e8/call ")
    #   write-slice-buffered(out, curr)
    #   write-buffered(out, "/disp32\n")
    #   # emit pops
    #   write-buffered(out, "81 0/subop/add %esp ")
    #   print-int32-buffered(out, words->write >> 1 - 4)
    #   write-buffered(out, "/imm32\n")
    #
    # . prolog
    55/push-ebp
    89/<- %ebp 4/r32/esp
    # . save registers
$emit-call:end:
    # . reclaim locals
    # . restore registers
    # . epilog
    89/<- %esp 5/r32/ebp
    5d/pop-to-ebp
    c3/return

next-word-string-or-expression-without-metadata:  # line : (address stream), word-slice : (address slice)
    # pseudocode:
    #   skip-chars-matching(line, ' ')
    #   if line->read >= line->write              # end of line
    #     out = {0, 0}
    #     return
    #   out->start = &line->data[line->read]
    #   if line->data[line->read] == '#'          # comment
    #     out.end = &line->data[line->write]      # skip to end of line
    #     return
    #   if line->data[line->read] == '"'          # string literal
    #     skip-string(line)
    #     out.end = &line->data[line->read]         # no metadata
    #     return
    #   if line->data[line->read] == '*'          # expression
    #     if line->data[line->read + 1] == ' '
    #       abort
    #     if line->data[line->read + 1] == '('
    #       skip-until-close-paren(line)
    #       if (line->data[line->read] != ')'
    #         abort
    #       ++line->data[line->read] to skip ')'
    #     out->end = &line->data[line->read]
    #     return
    #   if line->data[line->read] == ')'
    #     ++line->read to skip ')'
    #     # make sure there's nothing else of importance
    #     if line->read >= line->write
    #       out = {0, 0}
    #       return
    #     if line->data[line->read] != ' '
    #       abort
    #     skip-chars-matching-whitespace(line)
    #     if line->read >= line->write
    #       out = {0, 0}
    #       return
    #     if line->data[line->read] != '#'        # only thing permitted after ')' is a comment
    #       abort
    #     out.end = &line->data[line->write]      # skip to end of line
    #     return
    #   # default case: read a word -- but no metadata
    #   while true
    #     if line->read >= line->write
    #       break
    #     if line->data[line->read] == ' '
    #       break
    #     if line->data[line->read] == '/'
    #       abort
    #     ++line->read
    #   out.end = &line->data[line->read]
    #
    # registers:
    #   ecx: often line->read
    #   eax: often line->data[line->read]
    #
    # . prolog
    55/push-ebp
    89/<- %ebp 4/r32/esp
    # . save registers
    50/push-eax
    51/push-ecx
    56/push-esi
    57/push-edi
    # skip-chars-matching(line, ' ')
    # . . push args
    68/push 0x20/imm32/space
    ff 6/subop/push *(ebp+8)
    # . . call
    e8/call skip-chars-matching/disp32
    # . . discard args
    81 0/subop/add %esp 8/imm32
$next-word-string-or-expression-without-metadata:check0:
    # if (line->read >= line->write) clear out and return
    # . eax = line->read
    8b/-> *(esi+4) 0/r32/eax
    # . if (eax < line->write) goto next check
    3b/compare *esi 0/r32/eax
    7c/jump-if-lesser $next-word-string-or-expression-without-metadata:check-for-comment/disp8
    # . return out = {0, 0}
    c7 0/subop/copy *edi 0/imm32
    c7 0/subop/copy *(edi+4) 0/imm32
    e9/jump $next-word-string-or-expression-without-metadata:end/disp32
$next-word-string-or-expression-without-metadata:check-for-comment:
    # out->start = &line->data[line->read]
    8b/-> *(esi+4) 1/r32/ecx
    8d/copy-address *(esi+ecx+0xc) 0/r32/eax
    89/<- *edi 0/r32/eax
    # if (line->data[line->read] != '#') goto next check
    # . eax = line->data[line->read]
    31/xor %eax 0/r32/eax
    8a/copy-byte *(esi+ecx+0xc) 0/r32/AL
    # . if (eax != '#') goto next check
    3d/compare-eax-and 0x23/imm32/pound
    75/jump-if-not-equal $next-word-string-or-expression-without-metadata:check-for-string-literal/disp8
$next-word-string-or-expression-without-metadata:comment:
    # out->end = &line->data[line->write]
    8b/-> *esi 0/r32/eax
    8d/copy-address *(esi+eax+0xc) 0/r32/eax
    89/<- *(edi+4) 0/r32/eax
    # line->read = line->write  # skip rest of line
    8b/-> *esi 0/r32/eax
    89/<- *(esi+4) 0/r32/eax
    # return
    eb/jump $next-word-string-or-expression-without-metadata:end/disp8
$next-word-string-or-expression-without-metadata:check-for-string-literal:
    # if (line->data[line->read] != '"') goto next check
    3d/compare-eax-and 0x22/imm32/dquote
    75/jump-if-not-equal $next-word-string-or-expression-without-metadata:check-for-expression/disp8
$next-word-string-or-expression-without-metadata:string-literal:
    # skip-string(line)
    # . . push args
    56/push-esi
    # . . call
    e8/call skip-string/disp32
    # . . discard args
    81 0/subop/add %esp 4/imm32
    # out->end = &line->data[line->read]
    8b/-> *(esi+4) 1/r32/ecx
    8d/copy-address *(esi+ecx+0xc) 0/r32/eax
    89/<- *(edi+4) 0/r32/eax
    # return
    eb/jump $next-word-string-or-expression-without-metadata:end/disp8
$next-word-string-or-expression-without-metadata:check-for-expression:
    # if (line->data[line->read] != '*') goto next check
    3d/compare-eax-and 0x2a/imm32/asterisk
    75/jump-if-not-equal $next-word-string-or-expression-without-metadata:check-for-end-of-call/disp8
    # if (line->data[line->read + 1] == ' ') goto error1
    8a/copy-byte *(esi+ecx+0xd) 0/r32/AL
    3d/compare-eax-and 0x20/imm32/space
    74/jump-if-equal $next-word-string-or-expression-without-metadata:error1/disp8
    # if (line->data[line->read] != '(') goto regular word
    3d/compare-eax-and 0x28/imm32/open-paren
    75/jump-if-not-equal $next-word-string-or-expression-without-metadata:regular-word/disp8
$next-word-string-or-expression-without-metadata:paren:
    # skip-until-close-paren(line)
    # . . push args
    56/push-esi
    # . . call
    e8/call skip-until-close-paren/disp32
    # . . discard args
    81 0/subop/add %esp 4/imm32
    # if (line->data[line->read] != ')') goto error2
    # . eax = line->data[line->read]
    8b/-> *(esi+4) 1/r32/ecx
    8a/copy-byte *(esi+ecx+0xc) 0/r32/AL
    # . if (eax != ')') goto error2
    3d/compare-eax-and 0x29/imm32/close-paren
    75/jump-if-not-equal $next-word-string-or-expression-without-metadata:error2/disp8
    # skip ')'
    ff 0/subop/increment *(esi+4)
    # out->end = &line->data[line->read]
    8b/-> *(esi+4) 1/r32/ecx
    8d/copy-address *(esi+ecx+0xc) 0/r32/eax
    89/<- *(edi+4) 0/r32/eax
    # return
    eb/jump $next-word-string-or-expression-without-metadata:end/disp8
$next-word-string-or-expression-without-metadata:end:
    # . restore registers
    5f/pop-to-edi
    5e/pop-to-esi
    59/pop-to-ecx
    58/pop-to-eax
    # . epilog
    89/<- %esp 5/r32/ebp
    5d/pop-to-ebp
    c3/return

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