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authorKartik K. Agaram <vc@akkartik.com>2021-08-10 06:29:11 -0700
committerKartik K. Agaram <vc@akkartik.com>2021-08-10 06:29:11 -0700
commitb0a83af0e56a3f1d32059554c06734fff58bebc5 (patch)
treed8a62ca7502f03cf5be4f78dc1f0b6182a1bcd6c /120allocate.subx
parent179db5aeb6c51936242a33a4612d6f6c1dc88b88 (diff)
downloadmu-b0a83af0e56a3f1d32059554c06734fff58bebc5.tar.gz
slack: fix abort after load
I forgot about the null bytes that come from loading sectors.
Diffstat (limited to '120allocate.subx')
0 files changed, 0 insertions, 0 deletions
 

generated by cgit-pink 1.4.1-2-gfad0 (git 2.36.2.497.gbbea4dcf42) at 2024-12-23 06:50:23 +0000


 


lass='oid'>a8dd0d40 ^


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# Helper to check an array's bounds, and to abort if they're violated.
# Really only intended to be called from code generated by mu.subx.

== code

__check-mu-array-bounds:  # index: int, elem-size: int, arr-size: int, function-name: (addr array byte), array-name: (addr array byte)
    # . prologue
    55/push-ebp
    89/<- %ebp 4/r32/esp
    # . save registers
    50/push-eax
    51/push-ecx
    52/push-edx
    # . not bothering saving ebx; it's only clobbered if we're going to abort
    # ecx = arr-size
    8b/-> *(ebp+0x10) 1/r32/ecx
    # var overflow/edx: int = 0
    ba/copy-to-edx 0/imm32
    # var offset/eax: int = index * elem-size
    8b/-> *(ebp+8) 0/r32/eax
    f7 4/subop/multiply-eax-with *(ebp+0xc)
    # check for overflow
    81 7/subop/compare %edx 0/imm32
    0f 85/jump-if-!= __check-mu-array-bounds:overflow/disp32
    # check bounds
    39/compare %eax 1/r32/ecx
    0f 82/jump-if-unsigned< $__check-mu-array-bounds:end/disp32  # negative index should always abort
    # abort if necessary
    (draw-text-wrapping-right-then-down-from-cursor-over-full-screen 0 "fn " 3 0)  # 3=cyan
    (draw-text-wrapping-right-then-down-from-cursor-over-full-screen 0 *(ebp+0x14) 3 0)  # 3=cyan
    (draw-text-wrapping-right-then-down-from-cursor-over-full-screen 0 ": offset " 3 0)  # 3=cyan
    (draw-int32-hex-wrapping-right-then-down-from-cursor-over-full-screen 0 %eax 3 0)  # 3=cyan
    (draw-text-wrapping-right-then-down-from-cursor-over-full-screen 0 " is too large for array '" 3 0)  # 3=cyan
    (draw-text-wrapping-right-then-down-from-cursor-over-full-screen 0 *(ebp+0x18) 3 0)  # 3=cyan
    (draw-text-wrapping-right-then-down-from-cursor-over-full-screen 0 "'" 3 0)  # 3=cyan
    {
      eb/jump loop/disp8
    }
    # never gets here
$__check-mu-array-bounds:end:
    # . restore registers
    5a/pop-to-edx
    59/pop-to-ecx
    58/pop-to-eax
    # . epilogue
    89/<- %esp 5/r32/ebp
    5d/pop-to-ebp
    c3/return

__check-mu-array-bounds:overflow:
    (draw-text-wrapping-right-then-down-from-cursor-over-full-screen 0 "fn " 3 0)  # 3=cyan
    (draw-text-wrapping-right-then-down-from-cursor-over-full-screen 0 *(ebp+0x14) 3 0)  # 3=cyan
    (draw-text-wrapping-right-then-down-from-cursor-over-full-screen 0 ": offset to array '" 3 0)  # 3=cyan
    (draw-text-wrapping-right-then-down-from-cursor-over-full-screen 0 *(ebp+0x18) 3 0)  # 3=cyan
    (draw-text-wrapping-right-then-down-from-cursor-over-full-screen 0 "' overflowed 32 bits" 3 0)  # 3=cyan
    {
      eb/jump loop/disp8
    }
    # never gets here