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mu/linux/120allocate.subx
Kartik K. Agaram 827dd4a7fe start throwing error on duplicate label 
One less error that's only in the bootstrap phase.

On the other hand, for simplicity I got rid of the ability to override
the Entry label. One less special case, but we're also going further
from the ability to run subsets of layers. We haven't really been
exercising it for a long time, though (commit 7842, March 2021 when we
made baremetal the default).
2021-08-22 21:09:28 -07:00

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# Helper to dynamically allocate memory on the heap.
#
# We'd like to be able to write tests for functions that allocate memory,
# making assertions on the precise addresses used. To achieve this we'll pass
# in an *allocation descriptor* to allocate from.
#
# Allocation descriptors are also useful outside of tests. Assembly and machine
# code are of necessity unsafe languages, and one of the most insidious kinds
# of bugs unsafe languages expose us to are dangling pointers to memory that
# has been freed and potentially even reused for something totally different.
# To reduce the odds of such "use after free" errors, SubX programs tend to not
# reclaim and reuse dynamically allocated memory. (Running out of memory is far
# easier to debug.) Long-running programs that want to reuse memory are mostly
# on their own to be careful. However, they do get one bit of help: they can
# carve out chunks of memory and then allocate from them manually using this
# very same 'allocate' helper. They just need a new allocation descriptor for
# their book-keeping.
== data
# Allocations are returned in a handle, which consists of an alloc-id and a payload.
# The alloc-id helps detect use-after-free errors.
Handle-size: # (addr int)
8/imm32
# A default allocation descriptor for programs to use.
Heap: # allocation-descriptor
# curr
0/imm32
# limit
0/imm32
# a reasonable default
Heap-size: # int
0x800000/imm32/8MB
Next-alloc-id: # int
0x100/imm32 # save a few alloc ids for fake handles
== code
# instruction effective address register displacement immediate
# . op subop mod rm32 base index scale r32
# . 1-3 bytes 3 bits 2 bits 3 bits 3 bits 3 bits 2 bits 2 bits 0/1/2/4 bytes 0/1/2/4 bytes
#? # Let's start initializing the default allocation descriptor.
#?
#? Entry:
#? # initialize heap
#? # . Heap = new-segment(Heap-size)
#? # . . push args
#? 68/push Heap/imm32
#? ff 6/subop/push 0/mod/indirect 5/rm32/.disp32 . . . Heap-size/disp32 # push *Heap-size
#? # . . call
#? e8/call new-segment/disp32
#? # . . discard args
#? 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
e8/call run-tests/disp32 # 'run-tests' is a function created automatically by SubX. It calls all functions that start with 'test-'.
$array-equal-main:end:
# syscall_exit(Num-test-failures)
8b/copy 0/mod/indirect 5/rm32/.disp32 . . 3/r32/ebx Num-test-failures/disp32 # copy *Num-test-failures to ebx
e8/call syscall_exit/disp32
# Allocate and clear 'n' bytes of memory from an allocation-descriptor 'ad'.
# Abort if there isn't enough memory in 'ad'.
allocate: # ad: (addr allocation-descriptor), n: int, out: (addr handle _)
# . prologue
55/push-ebp
89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp
# . save registers
50/push-eax
# allocate-raw(ad, n, out)
# . . push args
ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 0x10/disp8 . # push *(ebp+16)
ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 0xc/disp8 . # push *(ebp+12)
ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 8/disp8 . # push *(ebp+8)
# . . call
e8/call allocate-raw/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
# eax = out->payload + 4
8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 0/r32/eax 0x10/disp8 . # copy *(ebp+16) to eax
8b/copy 1/mod/*+disp8 0/rm32/eax . . . 0/r32/eax 4/disp8 . # copy *(eax+4) to eax
05/add-to-eax 4/imm32
# zero-out(eax, n)
# . . push args
ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 0xc/disp8 . # push *(ebp+12)
50/push-eax
# . . call
e8/call zero-out/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
$allocate:end:
# . restore registers
58/pop-to-eax
# . epilogue
89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp
5d/pop-to-ebp
c3/return
# Claim the next 'n' bytes of memory starting at ad->curr and update ad->curr.
# Abort if there isn't enough memory in 'ad'.
allocate-raw: # ad: (addr allocation-descriptor), n: int, out: (addr handle _)
# . prologue
55/push-ebp
89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp
# . save registers
50/push-eax
51/push-ecx
52/push-edx
53/push-ebx
56/push-esi
57/push-edi
# ecx = ad
8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 1/r32/ecx 8/disp8 . # copy *(ebp+8) to ecx
# edx = out
8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 2/r32/edx 0x10/disp8 . # copy *(ebp+16) to edx
# ebx = n
8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 3/r32/ebx 0xc/disp8 . # copy *(ebp+12) to ebx
# out->alloc-id = Next-alloc-id
8b/copy 0/mod/indirect 5/rm32/.disp32 . . 0/r32/eax Next-alloc-id/disp32 # copy *Next-alloc-id to eax
89/copy 0/mod/indirect 2/rm32/edx . . . 0/r32/eax . . # copy eax to *edx
# out->payload = ad->curr
8b/copy 0/mod/indirect 1/rm32/ecx . . . 0/r32/eax . . # copy *ecx to eax
$allocate-raw:save-payload-in-eax:
89/copy 1/mod/*+disp8 2/rm32/edx . . . 0/r32/eax 4/disp8 . # copy eax to *(edx+4)
# *out->payload = Next-alloc-id
8b/copy 1/mod/*+disp8 2/rm32/edx . . . 7/r32/edi 4/disp8 . # copy *(edx+4) to edi
8b/copy 0/mod/indirect 5/rm32/.disp32 . . 6/r32/esi Next-alloc-id/disp32 # copy *Next-alloc-id to esi
89/copy 0/mod/indirect 7/rm32/edi . . . 6/r32/esi . . # copy esi to *edi
$allocate-raw:increment-next-alloc-id:
# increment *Next-alloc-id
ff 0/subop/increment 0/mod/indirect 5/rm32/.disp32 . . . Next-alloc-id/disp32 # increment *Next-alloc-id
# check if there's enough space
# TODO: move this check up before any state updates when we support error recovery
8d/copy-address 1/mod/*+disp8 4/rm32/sib 0/base/eax 3/index/ebx . 0/r32/eax 4/disp8 . # copy eax+ebx+4 to eax
3b/compare 1/mod/*+disp8 1/rm32/ecx . . . 0/r32/eax 4/disp8 . # compare eax with *(ecx+4)
73/jump-if->=-signed $allocate-raw:abort/disp8
$allocate-raw:commit:
# ad->curr += n+4
89/copy 0/mod/indirect 1/rm32/ecx . . . 0/r32/eax . . # copy eax to *ecx
$allocate-raw:end:
# . restore registers
5f/pop-to-edi
5e/pop-to-esi
5b/pop-to-ebx
5a/pop-to-edx
59/pop-to-ecx
58/pop-to-eax
# . epilogue
89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp
5d/pop-to-ebp
c3/return
$allocate-raw:abort:
# . _write(2/stderr, error)
# . . push args
68/push "allocate: failed\n"/imm32
68/push 2/imm32/stderr
# . . call
e8/call _write/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
# . syscall_exit(1)
bb/copy-to-ebx 1/imm32
e8/call syscall_exit/disp32
# never gets here
test-allocate-raw-success:
# . prologue
55/push-ebp
89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp
# var ad/ecx: allocation-descriptor
68/push 0/imm32/limit
68/push 0/imm32/curr
89/copy 3/mod/direct 1/rm32/ecx . . . 4/r32/esp . . # copy esp to ecx
# ad = new-segment(512)
# . . push args
51/push-ecx
68/push 0x200/imm32
# . . call
e8/call new-segment/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
# var expected-payload/ebx = ad->curr
8b/copy 0/mod/indirect 1/rm32/ecx . . . 3/r32/ebx . . # copy *ecx to ebx
# var h/edx: handle = {0, 0}
68/push 0/imm32
68/push 0/imm32
89/copy 3/mod/direct 2/rm32/edx . . . 4/r32/esp . . # copy esp to edx
# *Next-alloc-id = 0x34
c7 0/subop/copy 0/mod/indirect 5/rm32/.disp32 . . . Next-alloc-id/disp32 0x34/imm32 # copy to *Next-alloc-id
# allocate-raw(ad, 3, h)
# . . push args
52/push-edx
68/push 3/imm32
51/push-ecx
# . . call
e8/call allocate-raw/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
# check-ints-equal(h->alloc-id, 0x34, msg)
# . . push args
68/push "F - test-allocate-raw-success: sets alloc-id in handle"/imm32
68/push 0x34/imm32
ff 6/subop/push 0/mod/indirect 2/rm32/edx . . . . . . # push *edx
# . . call
e8/call check-ints-equal/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
# check-ints-equal(h->payload, expected-payload, msg)
# . . push args
68/push "F - test-allocate-raw-success: sets payload in handle"/imm32
53/push-ebx
ff 6/subop/push 1/mod/*+disp8 2/rm32/edx . . . . 4/disp8 . # push *(edx+4)
# . . call
e8/call check-ints-equal/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
# check-ints-equal(h->payload->alloc-id, 0x34, msg)
# . . push args
68/push "F - test-allocate-raw-success: sets alloc-id in payload"/imm32
68/push 0x34/imm32
ff 6/subop/push 0/mod/indirect 3/rm32/ebx . . . . . . # push *ebx
# . . call
e8/call check-ints-equal/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
# check-ints-equal(*Next-alloc-id, 0x35, msg)
# . . push args
68/push "F - test-allocate-raw-success: increments Next-alloc-id"/imm32
68/push 0x35/imm32
ff 6/subop/push 0/mod/indirect 5/rm32/.disp32 . . . Next-alloc-id/disp32 # push *Next-alloc-id
# . . call
e8/call check-ints-equal/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
# check-ints-equal(ad->curr - expected-payload, 3 + 4 for alloc-id, msg)
# . . push args
68/push "F - test-allocate-raw-success: updates allocation descriptor"/imm32
68/push 7/imm32
8b/copy 0/mod/indirect 1/rm32/ecx . . . 0/r32/eax . . # copy *ecx to eax
29/subtract 3/mod/direct 0/rm32/eax . . . 3/r32/ebx . . # subtract ebx from eax
50/push-eax
# . . call
e8/call check-ints-equal/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
# clean up
c7 0/subop/copy 0/mod/indirect 5/rm32/.disp32 . . . Next-alloc-id/disp32 0x100/imm32 # copy to *Next-alloc-id
# . reclaim locals
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0x10/imm32 # add to esp
# . epilogue
89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp
5d/pop-to-ebp
c3/return
lookup: # h: (handle _T) -> result/eax: (addr _T)
# . prologue
55/push-ebp
89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp
# . save registers
51/push-ecx
# eax = 0
31/xor 3/mod/direct 0/rm32/eax . . . 0/r32/eax . . # clear eax
# ecx = handle->alloc_id
8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 1/r32/ecx 8/disp8 . # copy *(ebp+8) to ecx
# if (ecx == 0) return 0
81 7/subop/compare 3/mod/direct 1/rm32/ecx . . . . . 0/imm32 # compare ecx
74/jump-if-= $lookup:end/disp8
# eax = handle->address (payload)
8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 0/r32/eax 0xc/disp8 . # copy *(ebp+12) to eax
# if (ecx != *eax) abort
39/compare 0/mod/indirect 0/rm32/eax . . . 1/r32/ecx . . # compare *eax and ecx
75/jump-if-!= $lookup:abort/disp8
# add 4 to eax
05/add-to-eax 4/imm32
$lookup:end:
# . restore registers
59/pop-to-ecx
# . epilogue
89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp
5d/pop-to-ebp
c3/return
$lookup:abort:
# . _write(2/stderr, msg)
# . . push args
68/push "lookup failed\n"/imm32
68/push 2/imm32/stderr
# . . call
e8/call _write/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
# . syscall_exit(1)
bb/copy-to-ebx 1/imm32/exit-status
e8/call syscall_exit/disp32
test-lookup-success:
# . prologue
55/push-ebp
89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp
# var ad/ebx: allocation-descriptor
68/push 0/imm32/limit
68/push 0/imm32/curr
89/copy 3/mod/direct 3/rm32/ebx . . . 4/r32/esp . . # copy esp to ebx
# ad = new-segment(512)
# . . push args
53/push-ebx
68/push 0x200/imm32
# . . call
e8/call new-segment/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
# var handle/ecx: handle
68/push 0/imm32/address
68/push 0/imm32/alloc-id
89/copy 3/mod/direct 1/rm32/ecx . . . 4/r32/esp . . # copy esp to ecx
# var old-top/edx = ad->curr
8b/copy 0/mod/indirect 3/rm32/ebx . . . 2/r32/edx . . # copy *ebx to edx
# allocate-raw(ad, 2, handle)
# . . push args
51/push-ecx
68/push 2/imm32/size
53/push-ebx
# . . call
e8/call allocate-raw/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
# eax = lookup(handle)
# . . push args
ff 6/subop/push 1/mod/*+disp8 1/rm32/ecx . . . . 4/disp8 . # push *(ecx+4)
ff 6/subop/push 0/mod/indirect 1/rm32/ecx . . . . . . # push *ecx
# . . call
e8/call lookup/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
# eax contains old top of heap, except skipping the alloc-id in the payload
# . check-ints-equal(eax, old-top+4, msg)
# . . push args
68/push "F - test-lookup-success"/imm32
81 0/subop/add 3/mod/direct 2/rm32/edx . . . . . 4/imm32 # add to edx
52/push-edx
50/push-eax
# . . call
e8/call check-ints-equal/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
# clean up
c7 0/subop/copy 0/mod/indirect 5/rm32/.disp32 . . . Next-alloc-id/disp32 0x100/imm32 # copy to *Next-alloc-id
# . reclaim locals
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0x10/imm32 # add to esp
# . epilogue
89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp
5d/pop-to-ebp
c3/return
test-lookup-null-returns-null:
# . prologue
55/push-ebp
89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp
# var handle/ecx: handle
68/push 0/imm32/address
68/push 0/imm32/alloc-id
89/copy 3/mod/direct 1/rm32/ecx . . . 4/r32/esp . . # copy esp to ecx
# eax = lookup(handle)
# . . push args
ff 6/subop/push 1/mod/*+disp8 1/rm32/ecx . . . . 4/disp8 . # push *(ecx+4)
ff 6/subop/push 0/mod/indirect 1/rm32/ecx . . . . . . # push *ecx
# . . call
e8/call lookup/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
# check-ints-equal(eax, 0, msg)
# . . push args
68/push "F - test-lookup-null-returns-null"/imm32
68/push 0/imm32
50/push-eax
# . . call
e8/call check-ints-equal/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
# . reclaim locals
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
# . epilogue
89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp
5d/pop-to-ebp
c3/return
_pending-test-lookup-failure:
# . prologue
55/push-ebp
89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp
# var heap/esi: allocation-descriptor
68/push 0/imm32/limit
68/push 0/imm32/curr
89/copy 3/mod/direct 6/rm32/esi . . . 4/r32/esp . . # copy esp to esi
# heap = new-segment(512)
# . . push args
56/push-esi
68/push 0x200/imm32
# . . call
e8/call new-segment/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
# var h1/ecx: handle
68/push 0/imm32/address
68/push 0/imm32/alloc-id
89/copy 3/mod/direct 1/rm32/ecx . . . 4/r32/esp . . # copy esp to ecx
# var old_top/ebx = heap->curr
8b/copy 0/mod/indirect 6/rm32/esi . . . 3/r32/ebx . . # copy *esi to ebx
# first allocation, to h1
# . allocate(heap, 2, h1)
# . . push args
51/push-ecx
68/push 2/imm32/size
56/push-esi
# . . call
e8/call allocate/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
# reset heap->curr to mimic reclamation
89/copy 0/mod/indirect 6/rm32/esi . . . 3/r32/ebx . . # copy ebx to *esi
# second allocation that returns the same address as the first
# var h2/edx: handle
68/push 0/imm32/address
68/push 0/imm32/alloc-id
89/copy 3/mod/direct 2/rm32/edx . . . 4/r32/esp . . # copy esp to edx
# . allocate(heap, 2, h2)
# . . push args
52/push-edx
68/push 2/imm32/size
56/push-esi
# . . call
e8/call allocate/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
# check-ints-equal(h1->address, h2->address, msg)
# . . push args
68/push "F - test-lookup-failure"/imm32
ff 6/subop/push 1/mod/*+disp8 2/rm32/ecx . . . . 4/disp8 . # push *(edx+4)
ff 6/subop/push 1/mod/*+disp8 1/rm32/ecx . . . . 4/disp8 . # push *(ecx+4)
# . . call
e8/call check-ints-equal/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
# lookup(h1) should crash
# . . push args
ff 6/subop/push 1/mod/*+disp8 1/rm32/ecx . . . . 4/disp8 . # push *(ecx+4)
ff 6/subop/push 0/mod/indirect 1/rm32/ecx . . . . . . # push *ecx
# . . call
e8/call lookup/disp32
# should never get past this point
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
# clean up
c7 0/subop/copy 0/mod/indirect 5/rm32/.disp32 . . . Next-alloc-id/disp32 0x100/imm32 # copy to *Next-alloc-id
# . reclaim locals
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
# . epilogue
89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp
5d/pop-to-ebp
c3/return
# when comparing handles, just treat them as pure values
handle-equal?: # a: (handle _T), b: (handle _T) -> result/eax: boolean
# . prologue
55/push-ebp
89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp
# . save registers
51/push-ecx
# eax = false
b8/copy-to-eax 0/imm32/false
$handle-equal?:compare-alloc-id:
# ecx = a->alloc_id
8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 1/r32/ecx 8/disp8 . # copy *(ebp+8) to ecx
# if (ecx != b->alloc_id) return false
39/compare 1/mod/*+disp8 5/rm32/ebp . . . 1/r32/ecx 0x10/disp8 . # compare ecx and *(ebp+16)
75/jump-if-!= $handle-equal?:end/disp8
$handle-equal?:compare-address:
# ecx = handle->address
8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 1/r32/ecx 0xc/disp8 . # copy *(ebp+12) to ecx
# if (ecx != b->address) return false
39/compare 1/mod/*+disp8 5/rm32/ebp . . . 1/r32/ecx 0x14/disp8 . # compare ecx and *(ebp+20)
75/jump-if-!= $handle-equal?:end/disp8
$handle-equal?:return-true:
# return true
b8/copy-to-eax 1/imm32/true
$handle-equal?:end:
# . restore registers
59/pop-to-ecx
# . epilogue
89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp
5d/pop-to-ebp
c3/return
copy-handle: # src: (handle _T), dest: (addr handle _T)
# . prologue
55/push-ebp
89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp
# . save registers
50/push-eax
51/push-ecx
# ecx = dest
8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 1/r32/ecx 0x10/disp8 . # copy *(ebp+16) to ecx
# *dest = src
8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 0/r32/eax 8/disp8 . # copy *(ebp+8) to eax
89/copy 0/mod/indirect 1/rm32/ecx . . . 0/r32/eax . . # copy eax to *ecx
8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 0/r32/eax 0xc/disp8 . # copy *(ebp+12) to eax
89/copy 1/mod/*+disp8 1/rm32/ecx . . . 0/r32/eax 4/disp8 . # copy eax to *(ecx+4)
$copy-handle:end:
# . restore registers
59/pop-to-ecx
58/pop-to-eax
# . epilogue
89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp
5d/pop-to-ebp
c3/return
# helper: create a nested allocation descriptor (useful for tests)
allocate-region: # ad: (addr allocation-descriptor), n: int, out: (addr handle allocation-descriptor)
# . prologue
55/push-ebp
89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp
# . save registers
50/push-eax
51/push-ecx
# allocate(ad, n, out)
# . . push args
ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 0x10/disp8 . # push *(ebp+16)
ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 0xc/disp8 . # push *(ebp+12)
ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 8/disp8 . # push *(ebp+8)
# . . call
e8/call allocate/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
# eax = out->payload
8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 0/r32/eax 0x10/disp8 . # copy *(ebp+16) to eax
8b/copy 1/mod/*+disp8 0/rm32/eax . . . 0/r32/eax 4/disp8 . # copy *(eax+4) to eax
# skip payload->allocid
05/add-to-eax 4/imm32
# if (eax == 0) abort
3d/compare-eax-and 0/imm32
74/jump-if-= $allocate-region:abort/disp8
# earmark 8 bytes at the start for a new allocation descriptor
# . *eax = eax + 8
89/copy 3/mod/direct 1/rm32/ecx . . . 0/r32/eax . . # copy eax to ecx
81 0/subop/add 3/mod/direct 1/rm32/ecx . . . . . 8/imm32 # add to ecx
89/copy 0/mod/indirect 0/rm32/eax . . . 1/r32/ecx . . # copy ecx to *eax
# . *(eax+4) = eax + n
89/copy 3/mod/direct 1/rm32/ecx . . . 0/r32/eax . . # copy eax to ecx
03/add 1/mod/*+disp8 5/rm32/ebp . . . 1/r32/ecx 0xc/disp8 . # add *(ebp+12) to ecx
89/copy 1/mod/*+disp8 0/rm32/eax . . . 1/r32/ecx 4/disp8 . # copy ecx to *(eax+4)
# . restore registers
59/pop-to-ecx
58/pop-to-eax
# . epilogue
89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp
5d/pop-to-ebp
c3/return
# We could create a more general '$abort' jump target, but then we'd need to do
# a conditional jump followed by loading the error message and an unconditional
# jump. Or we'd need to unconditionally load the error message before a
# conditional jump, even if it's unused the vast majority of the time. This way
# we bloat a potentially cold segment in RAM so we can abort with a single
# instruction.
$allocate-region:abort:
# . _write(2/stderr, error)
# . . push args
68/push "allocate-region: failed to allocate\n"/imm32
68/push 2/imm32/stderr
# . . call
e8/call _write/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
# . syscall_exit(1)
bb/copy-to-ebx 1/imm32
e8/call syscall_exit/disp32
# never gets here
# Claim the next 'n+4' bytes of memory and initialize the first 4 to n.
# Abort if there isn't enough memory in 'ad'.
allocate-array: # ad: (addr allocation-descriptor), n: int, out: (addr handle _)
# . prologue
55/push-ebp
89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp
# . save registers
50/push-eax
51/push-ecx
52/push-edx
# ecx = n
8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 1/r32/ecx 0xc/disp8 . # copy *(ebp+12) to ecx
# var size/edx: int = n+4
8d/copy-address 1/mod/*+disp8 1/rm32/ecx . . . 2/r32/edx 4/disp8 . # copy ecx+4 to edx
# allocate(ad, size, out)
# . . push args
ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 0x10/disp8 . # push *(ebp+16)
52/push-edx
ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 8/disp8 . # push *(ebp+8)
# . . call
e8/call allocate/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
# *out->payload = n
8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 0/r32/eax 0x10/disp8 . # copy *(ebp+16) to eax
8b/copy 1/mod/*+disp8 0/rm32/eax . . . 0/r32/eax 4/disp8 . # copy *(eax+4) to eax
# . skip payload->allocid
05/add-to-eax 4/imm32
# .
89/copy 0/mod/indirect 0/rm32/eax . . . 1/r32/ecx . . # copy ecx to *eax
$allocate-array:end:
# . restore registers
5a/pop-to-edx
59/pop-to-ecx
58/pop-to-eax
# . epilogue
89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp
5d/pop-to-ebp
c3/return
test-allocate-array:
# . prologue
55/push-ebp
89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp
# var ad/ecx: allocation-descriptor
68/push 0/imm32/limit
68/push 0/imm32/curr
89/copy 3/mod/direct 1/rm32/ecx . . . 4/r32/esp . . # copy esp to ecx
# ad = new-segment(512)
# . . push args
51/push-ecx
68/push 0x200/imm32
# . . call
e8/call new-segment/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
# var expected-payload/ebx = ad->curr
8b/copy 0/mod/indirect 1/rm32/ecx . . . 3/r32/ebx . . # copy *ecx to ebx
# var h/edx: handle = {0, 0}
68/push 0/imm32
68/push 0/imm32
89/copy 3/mod/direct 2/rm32/edx . . . 4/r32/esp . . # copy esp to edx
# *Next-alloc-id = 0x34
c7 0/subop/copy 0/mod/indirect 5/rm32/.disp32 . . . Next-alloc-id/disp32 0x34/imm32 # copy to *Next-alloc-id
# allocate-array(ad, 3, h)
# . . push args
52/push-edx
68/push 3/imm32
51/push-ecx
# . . call
e8/call allocate-array/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
# check-ints-equal(h->alloc-id, 0x34, msg)
# . . push args
68/push "F - test-allocate-array: sets alloc-id in handle"/imm32
68/push 0x34/imm32
ff 6/subop/push 0/mod/indirect 2/rm32/edx . . . . . . # push *edx
# . . call
e8/call check-ints-equal/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
# check-ints-equal(h->payload, expected-payload, msg)
# . . push args
68/push "F - test-allocate-array: sets payload in handle"/imm32
53/push-ebx
ff 6/subop/push 1/mod/*+disp8 2/rm32/edx . . . . 4/disp8 . # push *(edx+4)
# . . call
e8/call check-ints-equal/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
# check-ints-equal(h->payload->alloc-id, 0x34, msg)
# . . push args
68/push "F - test-allocate-array: sets alloc-id in payload"/imm32
68/push 0x34/imm32
ff 6/subop/push 0/mod/indirect 3/rm32/ebx . . . . . . # push *ebx
# . . call
e8/call check-ints-equal/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
# check-ints-equal(h->payload->size, 3, msg)
# . . push args
68/push "F - test-allocate-array: sets array size in payload"/imm32
68/push 3/imm32
ff 6/subop/push 1/mod/*+disp8 3/rm32/ebx . . . . 4/disp8 . # push *(ebx+4)
# . . call
e8/call check-ints-equal/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
# check-ints-equal(*Next-alloc-id, 0x35, msg)
# . . push args
68/push "F - test-allocate-array: increments Next-alloc-id"/imm32
68/push 0x35/imm32
ff 6/subop/push 0/mod/indirect 5/rm32/.disp32 . . . Next-alloc-id/disp32 # push *Next-alloc-id
# . . call
e8/call check-ints-equal/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
# check-ints-equal(ad->curr - expected-payload, 3 + 4 for alloc-id + 4 for array size, msg)
# . . push args
68/push "F - test-allocate-array: updates allocation descriptor"/imm32
68/push 0xb/imm32
8b/copy 0/mod/indirect 1/rm32/ecx . . . 0/r32/eax . . # copy *ecx to eax
29/subtract 3/mod/direct 0/rm32/eax . . . 3/r32/ebx . . # subtract ebx from eax
50/push-eax
# . . call
e8/call check-ints-equal/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
# clean up
c7 0/subop/copy 0/mod/indirect 5/rm32/.disp32 . . . Next-alloc-id/disp32 1/imm32 # copy to *Next-alloc-id
# . reclaim locals
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0x10/imm32 # add to esp
# . epilogue
89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp
5d/pop-to-ebp
c3/return
copy-array: # ad: (addr allocation-descriptor), src: (addr array _T), out: (addr handle array _T)
# . prologue
55/push-ebp
89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp
# . save registers
50/push-eax
51/push-ecx
52/push-edx
56/push-esi
# esi = src
8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 6/r32/esi 0xc/disp8 . # copy *(ebp+12) to esi
# var size/ecx: int = src->size+4
8b/copy 0/mod/indirect 6/rm32/esi . . . 1/r32/ecx . . # copy *esi to ecx
81 0/subop/add 3/mod/direct 1/rm32/ecx . . . . . 4/imm32 # add to ecx
# allocate(ad, size, out)
# . . push args
ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 0x10/disp8 . # push *(ebp+16)
51/push-ecx
ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 8/disp8 . # push *(ebp+8)
# . . call
e8/call allocate/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
# var payload/eax: (addr byte) = out->payload
8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 0/r32/eax 0x10/disp8 . # copy *(ebp+16) to eax
8b/copy 1/mod/*+disp8 0/rm32/eax . . . 0/r32/eax 4/disp8 . # copy *(eax+4) to eax
# . skip payload->allocid
05/add-to-eax 4/imm32
# var max/ecx: (addr byte) = payload + size
01/add 3/mod/direct 1/rm32/ecx . . . 0/r32/eax . . # add eax to ecx
# _append-4(payload, max, src, &src->data[src->size])
# . . push &src->data[src->size]
8b/copy 0/mod/indirect 6/rm32/esi . . . 2/r32/edx . . # copy *esi to edx
8d/copy-address 1/mod/*+disp8 4/rm32/sib 6/base/esi 2/index/edx . 2/r32/edx 4/disp8 . # copy esi+edx+4 to edx
52/push-edx
# . . push src
56/push-esi
# . . push max
51/push-ecx
# . . push payload
50/push-eax
# . . call
e8/call _append-4/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0x10/imm32 # add to esp
$copy-array:end:
# . restore registers
5e/pop-to-esi
5a/pop-to-edx
59/pop-to-ecx
58/pop-to-eax
# . epilogue
89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp
5d/pop-to-ebp
c3/return
test-copy-array:
# . prologue
55/push-ebp
89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp
# var src/esi: (addr array int) = [3, 4, 5]
68/push 5/imm32
68/push 4/imm32
68/push 3/imm32
68/push 0xc/imm32/size
89/copy 3/mod/direct 6/rm32/esi . . . 4/r32/esp . . # copy esp to esi
# var ad/ecx: allocation-descriptor
68/push 0/imm32/limit
68/push 0/imm32/curr
89/copy 3/mod/direct 1/rm32/ecx . . . 4/r32/esp . . # copy esp to ecx
# ad = new-segment(512)
# . . push args
51/push-ecx
68/push 0x200/imm32
# . . call
e8/call new-segment/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
# var expected-payload/ebx = ad->curr
8b/copy 0/mod/indirect 1/rm32/ecx . . . 3/r32/ebx . . # copy *ecx to ebx
# var h/edx: handle = {0, 0}
68/push 0/imm32
68/push 0/imm32
89/copy 3/mod/direct 2/rm32/edx . . . 4/r32/esp . . # copy esp to edx
# *Next-alloc-id = 0x34
c7 0/subop/copy 0/mod/indirect 5/rm32/.disp32 . . . Next-alloc-id/disp32 0x34/imm32 # copy to *Next-alloc-id
# copy-array(ad, src, h)
# . . push args
52/push-edx
56/push-esi
51/push-ecx
# . . call
e8/call copy-array/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
# check-ints-equal(h->alloc-id, 0x34, msg)
# . . push args
68/push "F - test-copy-array: sets alloc-id in handle"/imm32
68/push 0x34/imm32
ff 6/subop/push 0/mod/indirect 2/rm32/edx . . . . . . # push *edx
# . . call
e8/call check-ints-equal/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
# check-ints-equal(h->payload, expected-payload, msg)
# . . push args
68/push "F - test-copy-array: sets payload in handle"/imm32
53/push-ebx
ff 6/subop/push 1/mod/*+disp8 2/rm32/edx . . . . 4/disp8 . # push *(edx+4)
# . . call
e8/call check-ints-equal/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
# check-ints-equal(h->payload->alloc-id, 0x34, msg)
# . . push args
68/push "F - test-copy-array: sets alloc-id in payload"/imm32
68/push 0x34/imm32
ff 6/subop/push 0/mod/indirect 2/rm32/edx . . . . . . # push *edx
# . . call
e8/call check-ints-equal/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
# var payload/eax: (addr int) = lookup(h)
# . . push args
ff 6/subop/push 1/mod/*+disp8 2/rm32/edx . . . . 4/disp8 . # push *(edx+4)
ff 6/subop/push 0/mod/indirect 2/rm32/edx . . . . . . # push *edx
# . . call
e8/call lookup/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
# check-ints-equal(payload->size, 0xc, msg)
# . . push args
68/push "F - test-copy-array: sets array size in payload"/imm32
68/push 0xc/imm32
ff 6/subop/push 0/mod/indirect 0/rm32/eax . . . . . . # push *eax
# . . call
e8/call check-ints-equal/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
# check-ints-equal(*Next-alloc-id, 0x35, msg)
# . . push args
68/push "F - test-copy-array: increments Next-alloc-id"/imm32
68/push 0x35/imm32
ff 6/subop/push 0/mod/indirect 5/rm32/.disp32 . . . Next-alloc-id/disp32 # push *Next-alloc-id
# . . call
e8/call check-ints-equal/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
# check-ints-equal(ad->curr - expected-payload, 12 + 4 for alloc-id + 4 for size, msg)
# . . push args
68/push "F - test-copy-array: updates allocation descriptor"/imm32
68/push 0x14/imm32
8b/copy 0/mod/indirect 1/rm32/ecx . . . 0/r32/eax . . # copy *ecx to eax
29/subtract 3/mod/direct 0/rm32/eax . . . 3/r32/ebx . . # subtract ebx from eax
50/push-eax
# . . call
e8/call check-ints-equal/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
# clean up
c7 0/subop/copy 0/mod/indirect 5/rm32/.disp32 . . . Next-alloc-id/disp32 1/imm32 # copy to *Next-alloc-id
# . reclaim locals
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0x20/imm32 # add to esp
# . epilogue
89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp
5d/pop-to-ebp
c3/return
# Fill a region of memory with zeroes.
zero-out: # start: (addr byte), size: int
# pseudocode:
# curr/esi = start
# i/ecx = 0
# while true
# if (i >= size) break
# *curr = 0
# ++curr
# ++i
#
# . prologue
55/push-ebp
89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp
# . save registers
50/push-eax
51/push-ecx
52/push-edx
56/push-esi
# curr/esi = start
8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 6/r32/esi 8/disp8 . # copy *(ebp+8) to esi
# var i/ecx: int = 0
31/xor 3/mod/direct 1/rm32/ecx . . . 1/r32/ecx . . # clear ecx
# edx = size
8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 2/r32/edx 0xc/disp8 . # copy *(ebp+12) to edx
$zero-out:loop:
# if (i >= size) break
39/compare 3/mod/direct 1/rm32/ecx . . . 2/r32/edx . . # compare ecx with edx
7d/jump-if->= $zero-out:end/disp8
# *curr = 0
c6 0/subop/copy-byte 0/mod/direct 6/rm32/esi . . . . . 0/imm8 # copy byte to *esi
# ++curr
46/increment-esi
# ++i
41/increment-ecx
eb/jump $zero-out:loop/disp8
$zero-out:end:
# . restore registers
5e/pop-to-esi
5a/pop-to-edx
59/pop-to-ecx
58/pop-to-eax
# . epilogue
89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp
5d/pop-to-ebp
c3/return
test-zero-out:
# . prologue
55/push-ebp
89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp
# region/ecx = 34, 35, 36, 37
68/push 0x37363534/imm32
89/copy 3/mod/direct 1/rm32/ecx . . . 4/r32/esp . . # copy esp to ecx
# zero-out(ecx, 3)
# . . push args
68/push 3/imm32/size
51/push-ecx
# . . call
e8/call zero-out/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
# first 3 bytes cleared, fourth left alone
# . check-ints-equal(*ecx, 0x37000000, msg)
# . . push args
68/push "F - test-zero-out"/imm32
68/push 0x37000000/imm32
ff 6/subop/push 0/mod/indirect 1/rm32/ecx . . . . . . # push *ecx
# . . call
e8/call check-ints-equal/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
# . reclaim locals
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 4/imm32 # add to esp
# . epilogue
89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp
5d/pop-to-ebp
c3/return
# . . vim:nowrap:textwidth=0
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