path: root/100array-equal.subx

# Comparing arrays of numbers.

== code

array-equal?:  # a: (addr array int), b: (addr array int) -> eax: boolean
    # pseudocode:
    #   lena = a->length
    #   if (lena != b->length) return false
    #   i = 0
    #   curra = a->data
    #   currb = b->data
    #   while i < lena
    #     i1 = *curra
    #     i2 = *currb
    #     if (c1 != c2) return false
    #     i+=4, curra+=4, currb+=4
    #   return true
    #
    # registers:
    #   i: ecx
    #   lena: edx
    #   curra: esi
    #   currb: edi
    #   i1: eax
    #   i2: ebx
    #
    # . 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
    # esi = a
    8b/-> *(ebp+8) 6/r32/esi
    # edi = b
    8b/-> *(ebp+0xc) 7/r32/edi
    # var lena/edx: int = a->length
    8b/-> *esi 2/r32/edx
$array-equal?:lengths:
    # if (lena != b->length) return false
    39/compare *edi 2/r32/edx
    75/jump-if-!= $array-equal?:false/disp8
    # var curra/esi: (addr byte) = a->data
    81 0/subop/add %esi 4/imm32
    # var currb/edi: (addr byte) = b->data
    81 0/subop/add %edi 4/imm32
    # var i/ecx: int = 0
    31/xor-with %ecx 1/r32/ecx
    # var vala/eax: int
    # var valb/ebx: int
$array-equal?:loop:
    # if (i >= lena) return true
    39/compare %ecx 2/r32/edx
    7d/jump-if->= $array-equal?:true/disp8
    # var vala/eax: int = *curra
    8b/-> *esi 0/r32/eax
    # var valb/ebx: int = *currb
    8b/-> *edi 3/r32/ebx
    # if (vala != valb) return false
    39/compare %eax 3/r32/ebx
    75/jump-if-!= $array-equal?:false/disp8
    # i += 4
    81 0/subop/add %ecx 4/imm32
    # currs += 4
    81 0/subop/add %esi 4/imm32
    # currb += 4
    81 0/subop/add %edi 4/imm32
    eb/jump $array-equal?:loop/disp8
$array-equal?:true:
    b8/copy-to-eax 1/imm32
    eb/jump $array-equal?:end/disp8
$array-equal?:false:
    b8/copy-to-eax 0/imm32
$array-equal?: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-compare-empty-with-empty-array:
    # . prologue
    55/push-ebp
    89/<- %ebp 4/r32/esp
    # var ecx: (array _) = []
    68/push 0/imm32/size
    89/<- %ecx 4/r32/esp
    # var edx: (array _) = []
    68/push 0/imm32/size
    89/<- %edx 4/r32/esp
    #
    (array-equal? %ecx %edx)  # => eax
    (check-ints-equal %eax 1 "F - test-compare-empty-with-empty-array")
    # . epilogue
    89/<- %esp 5/r32/ebp
    5d/pop-to-ebp
    c3/return

test-compare-empty-with-non-empty-array:  # also checks length-mismatch code path
    # . prologue
    55/push-ebp
    89/<- %ebp 4/r32/esp
    # var ecx: (array int) = [1]
    68/push 1/imm32
    68/push 4/imm32/size
    89/<- %ecx 4/r32/esp
    # var edx: (array int) = []
    68/push 0/imm32/size
    89/<- %edx 4/r32/esp
    #
    (array-equal? %ecx %edx)  # => eax
    (check-ints-equal %eax 0 "F - test-compare-empty-with-non-empty-array")
    # . epilogue
    89/<- %esp 5/r32/ebp
    5d/pop-to-ebp
    c3/return

test-compare-equal-arrays:
    # . prologue
    55/push-ebp
    89/<- %ebp 4/r32/esp
    # var ecx: (array int) = [1, 2, 3]
    68/push 3/imm32
    68/push 2/imm32
    68/push 1/imm32
    68/push 0xc/imm32/size
    89/<- %ecx 4/r32/esp
    # var edx: (array int) = [1, 2, 3]
    68/push 3/imm32
    68/push 2/imm32
    68/push 1/imm32
    68/push 0xc/imm32/size
    89/<- %edx 4/r32/esp
    #
    (array-equal? %ecx %edx)  # => eax
    (check-ints-equal %eax 1 "F - test-compare-equal-arrays")
    # . epilogue
    89/<- %esp 5/r32/ebp
    5d/pop-to-ebp
    c3/return

test-compare-inequal-arrays-equal-lengths:
    # . prologue
    55/push-ebp
    89/<- %ebp 4/r32/esp
    # var ecx: (array int) = [1, 4, 3]
    68/push 3/imm32
    68/push 4/imm32
    68/push 1/imm32
    68/push 0xc/imm32/size
    89/<- %ecx 4/r32/esp
    # var edx: (array int) = [1, 2, 3]
    68/push 3/imm32
    68/push 2/imm32
    68/push 1/imm32
    68/push 0xc/imm32/size
    89/<- %edx 4/r32/esp
    #
    (array-equal? %ecx %edx)  # => eax
    (check-ints-equal %eax 0 "F - test-compare-inequal-arrays-equal-lengths")
    # . epilogue
    89/<- %esp 5/r32/ebp
    5d/pop-to-ebp
    c3/return

parse-array-of-ints:  # ad: (addr allocation-descriptor), s: (addr string) -> result/eax: (handle array int)
    # pseudocode
    #   end = &s->data[s->length]
    #   curr = s->data
    #   size = 0
    #   while true
    #     if (curr >= end) break
    #     curr = skip-chars-matching-in-slice(curr, end, ' ')
    #     if (curr >= end) break
    #     curr = skip-chars-not-matching-in-slice(curr, end, ' ')
    #     ++size
    #   result = allocate(ad, (size+1)*4)
    #   result->size = (size+1)*4
    #   var slice: slice = {s->data, 0}
    #   out = result->data
    #   while true
    #     if (slice->start >= end) break
    #     slice->start = skip-chars-matching-in-slice(slice->start, end, ' ')
    #     if (slice->start >= end) break
    #     slice->end = skip-chars-not-matching-in-slice(slice->start, end, ' ')
    #     *out = parse-hex-int-from-slice(slice)
    #     out += 4
    #     slice->start = slice->end
    #   return result
    #
    # . 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
    # esi = s
    8b/-> *(ebp+0xc) 6/r32/esi
    # var curr/ecx: (addr byte) = s->data
    8d/copy-address *(esi+4) 1/r32/ecx
    # var end/edx: (addr byte) = &s->data[s->length]
    # . edx = s->length
    8b/-> *esi 2/r32/edx
    # . edx += curr
    01/add-to %edx 1/r32/ecx
    # var size/ebx: int = 0
    31/xor-with %ebx 3/r32/ebx
$parse-array-of-ints:loop1:
    # if (curr >= end) break
    39/compare %ecx 2/r32/edx
    73/jump-if-addr>= $parse-array-of-ints:break1/disp8
    # curr = skip-chars-matching-in-slice(curr, end, ' ')
    (skip-chars-matching-in-slice %ecx %edx 0x20)  # => eax
    89/<- %ecx 0/r32/eax
    # if (curr >= end) break
    39/compare %ecx 2/r32/edx
    73/jump-if-addr>= $parse-array-of-ints:break1/disp8
    # curr = skip-chars-not-matching-in-slice(curr, end, ' ')
    (skip-chars-not-matching-in-slice %ecx %edx 0x20)  # => eax
    89/<- %ecx 0/r32/eax
    # size += 4
    81 0/subop/add %ebx 4/imm32
    eb/jump $parse-array-of-ints:loop1/disp8
$parse-array-of-ints:break1:
    # var result/edi: (handle array int)
    89/<- %eax 3/r32/ebx
    05/add-to-eax 4/imm32
    (allocate *(ebp+8) %eax)
    89/<- %edi 0/r32/eax
    # result->size = size
    89/<- *edi 3/r32/ebx
$parse-array-of-ints:pass2:
    # var slice/ecx: slice = {s->data, 0}
    68/push 0/imm32/end
    8d/copy-address *(esi+4) 1/r32/ecx
    51/push-ecx
    89/<- %ecx 4/r32/esp
    # var out/ebx: (addr byte) = result->data
    8d/copy-address *(eax+4) 3/r32/ebx
$parse-array-of-ints:loop2:
    # if (slice->start >= end) break
    39/compare *ecx 2/r32/edx
    73/jump-if-addr>= $parse-array-of-ints:end/disp8
    # slice->start = skip-chars-matching-in-slice(slice->start, end, ' ')
    (skip-chars-matching-in-slice *ecx %edx 0x20)  # => eax
    89/<- *ecx 0/r32/eax
    # if (slice->start >= end) break
    39/compare *ecx 2/r32/edx
    73/jump-if-addr>= $parse-array-of-ints:end/disp8
    # slice->end = skip-chars-not-matching-in-slice(slice->start, end, ' ')
    (skip-chars-not-matching-in-slice *ecx %edx 0x20)  # => eax
    89/<- *(ecx+4) 0/r32/eax
    # *out = parse-hex-int-from-slice(slice)
    (parse-hex-int-from-slice %ecx)
    89/<- *ebx 0/r32/eax
    # out += 4
    81 0/subop/add %ebx 4/imm32
    # slice->start = slice->end
    8b/-> *(ecx+4) 0/r32/eax
    89/<- *ecx 0/r32/eax
    81 0/subop/add %ecx 4/imm32
    eb/jump $parse-array-of-ints:loop2/disp8
$parse-array-of-ints:end:
    # return edi
    89/<- %eax 7/r32/edi
    # . reclaim locals
    81 0/subop/add %esp 8/imm32
    # . 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-array-of-ints:
    # . prologue
    55/push-ebp
    89/<- %ebp 4/r32/esp
    # var ecx: (array int) = [1, 2, 3]
    68/push 3/imm32
    68/push 2/imm32
    68/push 1/imm32
    68/push 0xc/imm32/size
    89/<- %ecx 4/r32/esp
    #
    (parse-array-of-ints Heap "1 2 3")  # => eax
    (array-equal? %ecx %eax)  # => eax
    (check-ints-equal %eax 1 "F - test-parse-array-of-ints")
    # . epilogue
    89/<- %esp 5/r32/ebp
    5d/pop-to-ebp
    c3/return

test-parse-array-of-ints-empty:
    # - empty string = empty array
    # . prologue
    55/push-ebp
    89/<- %ebp 4/r32/esp
    #
    (parse-array-of-ints Heap "")  # => eax
    (check-ints-equal *eax 0 "F - test-parse-array-of-ints-empty")
    # . epilogue
    89/<- %esp 5/r32/ebp
    5d/pop-to-ebp
    c3/return

test-parse-array-of-ints-just-whitespace:
    # - just whitespace = empty array
    # . prologue
    55/push-ebp
    89/<- %ebp 4/r32/esp
    #
    (parse-array-of-ints Heap Space)  # => eax
    (check-ints-equal *eax 0 "F - test-parse-array-of-ints-empty")
    # . epilogue
    89/<- %esp 5/r32/ebp
    5d/pop-to-ebp
    c3/return

test-parse-array-of-ints-extra-whitespace:
    # . prologue
    55/push-ebp
    89/<- %ebp 4/r32/esp
    # var ecx: (array int) = [1, 2, 3]
    68/push 3/imm32
    68/push 2/imm32
    68/push 1/imm32
    68/push 0xc/imm32/size
    89/<- %ecx 4/r32/esp
    #
    (parse-array-of-ints Heap " 1 2  3  ")  # => eax
    (array-equal? %ecx %eax)  # => eax
    (check-ints-equal %eax 1 "F - test-parse-array-of-ints-extra-whitespace")
    # . epilogue
    89/<- %esp 5/r32/ebp
    5d/pop-to-ebp
    c3/return

# helper for later tests
# compare an array with a string representation of an array literal
check-array-equal:  # a: (addr array int), expected: (addr string), msg: (addr string)
    # . prologue
    55/push-ebp
    89/<- %ebp 4/r32/esp
    # . save registers
    50/push-eax
    # var b/ecx: (handle array int) = parse-array-of-ints(Heap, expected)
    (parse-array-of-ints Heap *(ebp+0xc))  # => eax
    89/<- %ecx 0/r32/eax
    #
    (array-equal? *(ebp+8) %ecx)
    (check-ints-equal %eax 1 *(ebp+0x10))
$check-array-equal:end:
    # . restore registers
    58/pop-to-eax
    # . epilogue
    89/<- %esp 5/r32/ebp
    5d/pop-to-ebp
    c3/return

test-check-array-equal:
    # . prologue
    55/push-ebp
    89/<- %ebp 4/r32/esp
    # var ecx: (array int) = [1, 2, 3]
    68/push 3/imm32
    68/push 2/imm32
    68/push 1/imm32
    68/push 0xc/imm32/size
    89/<- %ecx 4/r32/esp
    #
    (check-array-equal %ecx "1 2 3" "F - test-check-array-equal")
    # . epilogue
    89/<- %esp 5/r32/ebp
    5d/pop-to-ebp
    c3/return

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