# Helpers for decimal ints.

# if slice doesn't contain a decimal number, return 0
parse-decimal-int-from-slice:  # in: (addr slice) -> out/eax: int
    # . prologue
    55/push-ebp
    89/<- %ebp 4/r32/esp
    # . save registers
    51/push-ecx
    # ecx = in
    8b/-> *(ebp+8) 1/r32/ecx
    #
    (parse-decimal-int-helper *ecx *(ecx+4))  # => eax
$parse-decimal-int-from-slice:end:
    # . restore registers
    59/pop-to-ecx
    # . epilogue
    89/<- %esp 5/r32/ebp
    5d/pop-to-ebp
    c3/return

# if slice doesn't contain a decimal number, return 0
parse-decimal-int:  # in: (addr array byte) -> result/eax: int
    # . prologue
    55/push-ebp
    89/<- %ebp 4/r32/esp
    # . save registers
    51/push-ecx
    52/push-edx
    # eax = in
    8b/-> *(ebp+8) 0/r32/eax
    # var start/ecx: (addr byte) = &in->data
    8d/copy-address *(eax+4) 1/r32/ecx
    # var end/edx: (addr byte) = &in->data[in->size]
    8b/-> *eax 2/r32/edx
    8d/copy-address *(eax+edx+4) 2/r32/edx
    #
    (parse-decimal-int-helper %ecx %edx)  # => eax
$parse-decimal-int:end:
    # . restore registers
    5a/pop-to-edx
    59/pop-to-ecx
    # . epilogue
    89/<- %esp 5/r32/ebp
    5d/pop-to-ebp
    c3/return

parse-decimal-int-from-stream:  # in: (addr stream byte) -> result/eax: int
    # . prologue
    55/push-ebp
    89/<- %ebp 4/r32/esp
    # . save registers
    51/push-ecx
    52/push-edx
    # eax = in
    8b/-> *(ebp+8) 0/r32/eax
    # var start/ecx: (addr byte) = &in->data[in->read]
    8b/-> *(eax+4) 1/r32/ecx
    8d/copy-address *(eax+ecx+0xc) 1/r32/ecx
    # var end/edx: (addr byte) = &in->data[in->write]
    8b/-> *eax 2/r32/edx
    8d/copy-address *(eax+edx+0xc) 2/r32/edx
    #
    (parse-decimal-int-helper %ecx %edx)  # => eax
$parse-decimal-int-from-stream:end:
    # . restore registers
    5a/pop-to-edx
    59/pop-to-ecx
    # . epilogue
    89/<- %esp 5/r32/ebp
    5d/pop-to-ebp
    c3/return

parse-decimal-int-helper:  # start: (addr byte), end: (addr byte) -> result/eax: int
    # . prologue
    55/push-ebp
    89/<- %ebp 4/r32/esp
    # . save registers
    51/push-ecx
    52/push-edx
    53/push-ebx
    56/push-esi
    57/push-edi
    # var curr/esi: (addr byte) = start
    8b/-> *(ebp+8) 6/r32/esi
    # edi = end
    8b/-> *(ebp+0xc) 7/r32/edi
    # var negate?/edx: boolean = false
    ba/copy-to-edx 0/imm32/false
    # if (*curr == '-') ++curr, negate = true
    {
$parse-decimal-int-helper:negative:
      b8/copy-to-eax 0/imm32
      8a/copy-byte *esi 0/r32/AL
      3d/compare-eax-and 0x2d/imm32/-
      75/jump-if-!= break/disp8
      # . ++curr
      46/increment-esi
      # . negate = true
      ba/copy-to-edx  1/imm32/true
    }
    # spill negate?
    52/push-edx
    # var result/eax: int = 0
    b8/copy-to-eax 0/imm32
    # var digit/ecx: int = 0
    b9/copy-to-ecx 0/imm32
    # const TEN/ebx: int = 10
    bb/copy-to-ebx 0xa/imm32
    {
$parse-decimal-int-helper:loop:
      # if (curr >= in->end) break
      39/compare %esi 7/r32/edi
      73/jump-if-addr>= break/disp8
      # if !is-decimal-digit?(*curr) return 0
      8a/copy-byte *esi 1/r32/CL
      50/push-eax
      (is-decimal-digit? %ecx)  # => eax
      {
        3d/compare-eax-and 0/imm32/false
        75/jump-if-!= break/disp8
        58/pop-to-eax
        b8/copy-to-eax 0/imm32
        eb/jump $parse-decimal-int-helper:negate/disp8
      }
      58/pop-to-eax
      # digit = from-decimal-char(*curr)
      81 5/subop/subtract %ecx 0x30/imm32/zero
      # TODO: error checking
      # result = result * 10 + digit
      ba/copy-to-edx 0/imm32
      f7 4/subop/multiply-into-edx-eax %ebx
      # TODO: check edx for overflow
      01/add %eax 1/r32/ecx
      # ++curr
      46/increment-esi
      #
      eb/jump loop/disp8
    }
$parse-decimal-int-helper:negate:
    # if (negate?) result = -result
    5a/pop-to-edx
    {
      81 7/subop/compare %edx 0/imm32/false
      74/jump-if-= break/disp8
      f7 3/subop/negate %eax
    }
$parse-decimal-int-helper:end:
    # . restore registers
    5f/pop-to-edi
    5e/pop-to-esi
    5b/pop-to-ebx
    5a/pop-to-edx
    59/pop-to-ecx
    # . epilogue
    89/<- %esp 5/r32/ebp
    5d/pop-to-ebp
    c3/return

test-parse-decimal-int-from-slice-single-digit:
    # . prologue
    55/push-ebp
    89/<- %ebp 4/r32/esp
    # . save registers
    50/push-eax
    51/push-ecx
    # (eax..ecx) = "3"
    b8/copy-to-eax "3"/imm32
    8b/-> *eax 1/r32/ecx
    8d/copy-address *(eax+ecx+4) 1/r32/ecx
    05/add-to-eax 4/imm32
    # var slice/ecx: slice = {eax, ecx}
    51/push-ecx
    50/push-eax
    89/<- %ecx 4/r32/esp
    #
    (parse-decimal-int-from-slice %ecx)  # => eax
    (check-ints-equal %eax 3 "F - test-parse-decimal-int-from-slice-single-digit")
$test-parse-decimal-int-helper-single-digit:end:
    # . restore registers
    59/pop-to-ecx
    58/pop-to-eax
    # . epilogue
    89/<- %esp 5/r32/ebp
    5d/pop-to-ebp
    c3/return

test-parse-decimal-int-from-slice-multi-digit:
    # . prologue
    55/push-ebp
    89/<- %ebp 4/r32/esp
    # . save registers
    50/push-eax
    51/push-ecx
    # (eax..ecx) = "34"
    b8/copy-to-eax "34"/imm32
    8b/-> *eax 1/r32/ecx
    8d/copy-address *(eax+ecx+4) 1/r32/ecx
    05/add-to-eax 4/imm32
    # var slice/ecx: slice = {eax, ecx}
    51/push-ecx
    50/push-eax
    89/<- %ecx 4/r32/esp
    #
    (parse-decimal-int-from-slice %ecx)  # => eax
    (check-ints-equal %eax 0x22 "F - test-parse-decimal-int-from-slice-multi-digit")  # 34 in hex
$test-parse-decimal-int-helper-multi-digit:end:
    # . restore registers
    59/pop-to-ecx
    58/pop-to-eax
    # . epilogue
    89/<- %esp 5/r32/ebp
    5d/pop-to-ebp
    c3/return

test-parse-decimal-int-from-slice-zero:
    # . prologue
    55/push-ebp
    89/<- %ebp 4/r32/esp
    # . save registers
    50/push-eax
    51/push-ecx
    # (eax..ecx) = "00"
    b8/copy-to-eax "00"/imm32
    8b/-> *eax 1/r32/ecx
    8d/copy-address *(eax+ecx+4) 1/r32/ecx
    05/add-to-eax 4/imm32
    # var slice/ecx: slice = {eax, ecx}
    51/push-ecx
    50/push-eax
    89/<- %ecx 4/r32/esp
    #
    (parse-decimal-int-from-slice %ecx)  # => eax
    (check-ints-equal %eax 0 "F - test-parse-decimal-int-from-slice-zero")
$test-parse-decimal-int-helper-zero:end:
    # . restore registers
    59/pop-to-ecx
    58/pop-to-eax
    # . epilogue
    89/<- %esp 5/r32/ebp
    5d/pop-to-ebp
    c3/return

test-parse-decimal-int-from-slice-negative:
    # . prologue
    55/push-ebp
    89/<- %ebp 4/r32/esp
    # . save registers
    50/push-eax
    51/push-ecx
    # (eax..ecx) = "-3"
    b8/copy-to-eax "-3"/imm32
    8b/-> *eax 1/r32/ecx
    8d/copy-address *(eax+ecx+4) 1/r32/ecx
    05/add-to-eax 4/imm32
    # var slice/ecx: slice = {eax, ecx}
    51/push-ecx
    50/push-eax
    89/<- %ecx 4/r32/esp
    #
    (parse-decimal-int-from-slice %ecx)  # => eax
    (check-ints-equal %eax -3 "F - test-parse-decimal-int-from-slice-negative")
$test-parse-decimal-int-helper-negative:end:
    # . restore registers
    59/pop-to-ecx
    58/pop-to-eax
    # . epilogue
    89/<- %esp 5/r32/ebp
    5d/pop-to-ebp
    c3/return

test-parse-decimal-int-from-slice-multi-digit-negative:
    # . prologue
    55/push-ebp
    89/<- %ebp 4/r32/esp
    # . save registers
    50/push-eax
    51/push-ecx
    # (eax..ecx) = "-32"
    b8/copy-to-eax "-32"/imm32
    8b/-> *eax 1/r32/ecx
    8d/copy-address *(eax+ecx+4) 1/r32/ecx
    05/add-to-eax 4/imm32
    # var slice/ecx: slice = {eax, ecx}
    51/push-ecx
    50/push-eax
    89/<- %ecx 4/r32/esp
    #
    (parse-decimal-int-from-slice %ecx)  # => eax
    (check-ints-equal %eax -0x20 "F - test-parse-decimal-int-from-slice-multi-digit-negative")  # -32 in hex
$test-parse-decimal-int-helper-multi-digit-negative:end:
    # . restore registers
    59/pop-to-ecx
    58/pop-to-eax
    # . epilogue
    89/<- %esp 5/r32/ebp
    5d/pop-to-ebp
    c3/return

decimal-size:  # n: int -> result/eax: int
    # pseudocode:
    #   edi = 0
    #   eax = n
    #   if eax < 0
    #     ++edi  # for '-'
    #     negate eax
    #   while true
    #     edx = 0
    #     eax, edx = eax/10, eax%10
    #     ++edi
    #     if (eax == 0) break
    #   eax = edi
    #
    # . prologue
    55/push-ebp
    89/<- %ebp 4/r32/esp
    # . save registers
    51/push-ecx
    52/push-edx
    57/push-edi
    # edi = 0
    bf/copy-to-edi 0/imm32
    # eax = n
    8b/-> *(ebp+8) 0/r32/eax
    # if (n < 0) negate n, increment edi
    {
      3d/compare-eax-with 0/imm32
      7d/jump-if->= break/disp8
      f7 3/subop/negate %eax
      47/increment-edi
    }
    # const ten/ecx = 10
    b9/copy-to-ecx  0xa/imm32
    {
      ba/copy-to-edx 0/imm32
      f7 7/subop/idiv-edx-eax-by %ecx  # eax = edx:eax/10; edx = edx:eax%10
      47/increment-edi
      3d/compare-eax-and 0/imm32
      75/jump-if-!= loop/disp8
    }
$decimal-size:end:
    89/<- %eax 7/r32/edi
    # . restore registers
    5f/pop-to-edi
    5a/pop-to-edx
    59/pop-to-ecx
    # . epilogue
    89/<- %esp 5/r32/ebp
    5d/pop-to-ebp
    c3/return

test-decimal-size-of-zero:
    # . prologue
    55/push-ebp
    89/<- %ebp 4/r32/esp
    #
    (decimal-size 0)  # => eax
    (check-ints-equal %eax 1 "F - test-decimal-size-of-zero")
$test-decimal-size-of-zero:end:
    # . epilogue
    89/<- %esp 5/r32/ebp
    5d/pop-to-ebp
    c3/return

test-decimal-size-single-digit:
    # . prologue
    55/push-ebp
    89/<- %ebp 4/r32/esp
    #
    (decimal-size 4)  # => eax
    (check-ints-equal %eax 1 "F - test-decimal-size-single-digit")
$test-decimal-size-single-digit:end:
    # . epilogue
    89/<- %esp 5/r32/ebp
    5d/pop-to-ebp
    c3/return

test-decimal-size-multi-digit:
    # . prologue
    55/push-ebp
    89/<- %ebp 4/r32/esp
    #
    (decimal-size 0xa)  # => eax
    (check-ints-equal %eax 2 "F - test-decimal-size-multi-digit")
$test-decimal-size-multi-digit:end:
    # . epilogue
    89/<- %esp 5/r32/ebp
    5d/pop-to-ebp
    c3/return

test-decimal-size-single-digit-negative:
    # . prologue
    55/push-ebp
    89/<- %ebp 4/r32/esp
    #
    (decimal-size -4)  # => eax
    (check-ints-equal %eax 2 "F - test-decimal-size-single-digit-negative")
$test-decimal-size-single-digit-negative:end:
    # . epilogue
    89/<- %esp 5/r32/ebp
    5d/pop-to-ebp
    c3/return

test-decimal-size-multi-digit-negative:
    # . prologue
    55/push-ebp
    89/<- %ebp 4/r32/esp
    #
    (decimal-size -0xa)  # => eax
    (check-ints-equal %eax 3 "F - test-decimal-size-multi-digit-negative")
$test-decimal-size-multi-digit-negative:end:
    # . epilogue
    89/<- %esp 5/r32/ebp
    5d/pop-to-ebp
    c3/return