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| author | Kartik Agaram <vc@akkartik.com> | 2019-01-04 15:37:16 -0800 |
|---|---|---|
| committer | Kartik Agaram <vc@akkartik.com> | 2019-01-04 15:37:16 -0800 |
| commit | bc20cc3d4561152e1cef98cccc23488e02979c34 (patch) | |
| tree | 451618493aef569626b8f20726c77d689f7cbf9e /subx/066allocate.subx | |
| parent | 7b548ff5c5792422f1cc05896adf2f63f5af41c7 (diff) | |
| download | mu-bc20cc3d4561152e1cef98cccc23488e02979c34.tar.gz | |
4906 - helper to allocate streams on the heap
Diffstat (limited to 'subx/066allocate.subx')
| -rw-r--r-- | subx/066allocate.subx | 49 |
1 files changed, 49 insertions, 0 deletions
diff --git a/subx/066allocate.subx b/subx/066allocate.subx index 0e3b54f6..a4ea687c 100644 --- a/subx/066allocate.subx +++ b/subx/066allocate.subx @@ -149,4 +149,53 @@ test-allocate-failure: 5d/pop-to-EBP c3/return +# helper: create a nested allocation descriptor (useful for tests) +allocate-region: # ad : (address allocation-descriptor), n : int -> new-ad : (address allocation-descriptor) + # . prolog + 55/push-EBP + 89/copy 3/mod/direct 5/rm32/EBP . . . 4/r32/ESP . . # copy ESP to EBP + # . save registers + 51/push-ECX + # EAX = allocate(ad, n) + # . . push args + 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 . . . . . 8/imm32 # add to ESP + # if EAX == 0 abort + 81 7/subop/compare 3/mod/direct 0/rm32/EAX . . . . . 0/imm32 # compare EAX + 74/jump-if-equal $allocate-region:abort/disp8 + # earmark 8 bytes at the start for a new allocation descriptor + # . *EAX = EAX + 8 + 89/copy 3/mod/direct 1/rm32/ECX . . . 0/r32/EAX . . # copy EAX to ECX + 81 0/subop/add 3/mod/direct 1/rm32/ECX . . . . . 8/imm32 # add to ECX + 89/copy 0/mod/indirect 0/rm32/EAX . . . 1/r32/ECX . . # copy ECX to *EAX + # . *(EAX+4) = EAX + n + 89/copy 3/mod/direct 1/rm32/ECX . . . 0/r32/EAX . . # copy EAX to ECX + 03/add 1/mod/*+disp8 5/rm32/EBP . . . 1/r32/ECX 0xc/disp8 . # add *(EBP+12) to ECX + 89/copy 1/mod/*+disp8 0/rm32/EAX . . . 1/r32/ECX 4/disp8 . # copy ECX to *(EAX+4) + # . restore registers + 59/pop-to-ECX + # . epilog + 89/copy 3/mod/direct 4/rm32/ESP . . . 5/r32/EBP . . # copy EBP to ESP + 5d/pop-to-EBP + c3/return + +$allocate-region:abort: + # . _write(2/stderr, error) + # . . push args + 68/push "allocate-region: failed to allocate"/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 + b8/copy-to-EAX 1/imm32/exit + cd/syscall 0x80/imm8 + # never gets here + # . . vim:nowrap:textwidth=0 |