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This commit is contained in:
Kartik Agaram 2020-11-11 21:04:22 -08:00
parent 2be66922d6
commit 7d15b0884e
1 changed files with 32 additions and 19 deletions
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51
306files.subx
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@ -16,10 +16,39 @@ open: # filename: (addr array byte), write?: boolean, out: (addr handle buffere
# . save registers
50/push-eax
51/push-ecx
# var new-fd/ecx: fd
(open-fd *(ebp+8) *(ebp+0xc)) # => eax
89/<- %ecx 0/r32/eax
# if fd < 0 return
3d/compare-eax-with 0/imm32
7c/jump-if-< $open:end/disp8
# allocate a buffered-file
(allocate Heap 0x1010 *(ebp+0x10)) # file-buffer-size + 16 for other fields
# var out-addr/eax: (addr buffered-file)
8b/-> *(ebp+0x10) 0/r32/eax
(lookup *eax *(eax+4)) # => eax
# out-addr->size = 4KB
c7 0/subop/copy *(eax+0xc) 0x1000/imm32/file-buffer-size # Stream-size + 4 for fd
# out-addr->fd = fd
89/<- *eax 1/r32/ecx
$open:end:
# . restore registers
59/pop-to-ecx
58/pop-to-eax
# . epilogue
89/<- %esp 5/r32/ebp
5d/pop-to-ebp
c3/return
open-fd: # filename: (addr array byte), write?: boolean -> result/eax: fd
# . 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
# ecx = filename
8b/-> *(ebp+8) 1/r32/ecx
# var size/edx: int = filename->length + 1 for the trailing null character
@ -36,38 +65,22 @@ open: # filename: (addr array byte), write?: boolean, out: (addr handle buffere
(write %esi %ecx)
# spill edx
52/push-edx
# var fd/ecx: fd = open(filename)
# var fd/eax: fd = open(filename)
8d/copy-address *(esi+0xc) 3/r32/ebx
8b/-> *(ebp+0xc) 1/r32/ecx/flags
ba/copy-to-edx 0x180/imm32/permissions
e8/call syscall_open/disp32
89/<- %ecx 0/r32/eax
# restore edx
5a/pop-to-edx
# if fd < 0 return
3d/compare-eax-with 0/imm32
7c/jump-if-< $open:end/disp8
# allocate a buffered-file
(allocate Heap 0x1010 *(ebp+0x10)) # file-buffer-size + 16 for other fields
# var out-addr/edi: (addr buffered-file)
8b/-> *(ebp+0x10) 7/r32/edi
(lookup *edi *(edi+4)) # => eax
89/<- %edi 0/r32/eax
# out-addr->size = 4KB
c7 0/subop/copy *(edi+0xc) 0x1000/imm32/file-buffer-size # Stream-size + 4 for fd
# out-addr->fd = fd
89/<- *edi 1/r32/ecx
$open:end:
$open-fd:end:
# . reclaim locals
01/add-to %esp 2/r32/edx
81 0/subop/add %esp 0xc/imm32
# . 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/<- %esp 5/r32/ebp
5d/pop-to-ebp