https://github.com/akkartik/mu/blob/main/317abort.subx 
  1 # Dump a stack trace when you abort.
  2 
  3 == code
  4 
  5 abort:  # e: (addr array byte)
  6     # . prologue
  7     55/push-ebp
  8     89/<- %ebp 4/r32/esp
  9     #
 10     (set-cursor-position-on-real-screen 0 0)
 11     (draw-text-wrapping-right-then-down-from-cursor-over-full-screen 0 *(ebp+8) 0xf 0xc)  # 0/real-screen, 0xf/fg=white, 0xc/bg=red
 12     (dump-call-stack)
 13     # crash
 14     {
 15       eb/jump loop/disp8
 16     }
 17 
 18 # Helpers below this point are not intended to be reused; they assume the
 19 # program will soon crash. In particular, they destroy the heap.
 20 
 21 dump-call-stack:
 22     # . prologue
 23     55/push-ebp
 24     89/<- %ebp 4/r32/esp
 25     # . save registers
 26     50/push-eax
 27     51/push-ecx
 28     52/push-edx
 29     53/push-ebx
 30     # var labels/edx: (addr stream {start-address, label-slice} 0x5000)
 31     # start addresses are in ascending order
 32     81 5/subop/subtract %esp 0x3c000/imm32  # 0x5000 labels * 12 bytes per label
 33     68/push  0x3c000/imm32
 34     68/push  0/imm32/read
 35     68/push  0/imm32/write
 36     89/<- %edx 4/r32/esp
 37     #
 38     (load-debug-symbols %edx)  # destroys the heap
 39     # traverse the linked list of ebp pointers: https://wiki.osdev.org/Stack_Trace
 40     8b/-> *ebp 3/r32/ebx
 41     {
 42       # loop termination check
 43       81 7/subop/compare %ebx 0/imm32
 44       0f 84/jump-if-= break/disp32
 45       # loop body
 46       (draw-text-wrapping-right-then-down-from-cursor-over-full-screen 0 "\n" 0 0xc)
 47       (draw-int32-hex-wrapping-right-then-down-from-cursor-over-full-screen 0 *(ebx+4) 0xf 0xc)
 48       (draw-text-wrapping-right-then-down-from-cursor-over-full-screen 0 " " 0 0xc)
 49       (containing-function %edx *(ebx+4))  # => eax, ecx
 50       (draw-slice-wrapping-right-then-down-from-cursor-over-full-screen 0 %eax %ecx 0 0xc)
 51       # loop update
 52       8b/-> *ebx 3/r32/ebx
 53       #
 54       e9/jump loop/disp32
 55     }
 56 $dump-call-stack:end:
 57     # . reclaim locals
 58     81 0/subop/add %esp 0x100c/imm32
 59     # . restore registers
 60     5b/pop-to-ebx
 61     5a/pop-to-edx
 62     59/p
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<a href='https://github.com/akkartik/mu/blob/main/106stream.subx'>https://github.com/akkartik/mu/blob/main/106stream.subx</a>
<pre id='vimCodeElement'>
<span id="L1" class="LineNr"> 1 </span><span class="subxComment"># streams: data structure for operating on arrays in a stateful manner</span>
<span id="L2" class="LineNr"> 2 </span><span class="subxComment">#</span>
<span id="L3" class="LineNr"> 3 </span><span class="subxComment"># A stream looks like this:</span>
<span id="L4" class="LineNr"> 4 </span><span class="subxComment">#   write: int  # index at which writes go</span>
<span id="L5" class="LineNr"> 5 </span><span class="subxComment">#   read: int  # index that we've read until</span>
<span id="L6" class="LineNr"> 6 </span><span class="subxComment">#   data: (array byte)  # prefixed by size as usual</span>
<span id="L7" class="LineNr"> 7 </span><span class="subxComment">#</span>
<span id="L8" class="LineNr"> 8 </span><span class="subxComment"># some primitives for operating on streams:</span>
<span id="L9" class="LineNr"> 9