diff options
Diffstat (limited to '108write.subx')
| -rw-r--r-- | 108write.subx | 118 |
1 files changed, 88 insertions, 30 deletions
diff --git a/108write.subx b/108write.subx index 84060c62..43e9bf9b 100644 --- a/108write.subx +++ b/108write.subx @@ -1,46 +1,20 @@ -# write: like _write, but also support in-memory streams in addition to file -# descriptors. +# write: write to in-memory streams # -# Our first dependency-injected and testable primitive. We can pass it either -# a file descriptor or an address to a stream. If a file descriptor is passed -# in, we _write to it using the right syscall. If a 'fake file descriptor' or -# stream is passed in, we append to the stream. This lets us redirect output -# in tests and check it later. -# -# We assume our data segment will never begin at an address shorter than -# 0x08000000, so any smaller arguments are assumed to be real file descriptors. -# -# A stream looks like this: -# read: int # index at which to read next -# write: int # index at which writes go -# data: (array byte) # prefixed by size as usual +# We need to do this in machine code because streams need to be opaque types, +# and we don't yet support opaque types in Mu. == 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 -# TODO: come up with a way to signal when a write to disk fails -write: # f: fd or (addr stream byte), s: (addr array byte) +write: # f: (addr stream byte), s: (addr array byte) # . prologue 55/push-ebp 89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp # if (s == 0) return 81 7/subop/compare 1/mod/*+disp8 5/rm32/ebp . . . . 0xc/disp8 0/imm32 # compare *(ebp+12) 74/jump-if-= $write:end/disp8 - # if (f < 0x08000000) _write(f, s) and return # f can't be a user-mode address, so treat it as a kernel file descriptor - 81 7/subop/compare 1/mod/*+disp8 5/rm32/ebp . . . . 8/disp8 0x08000000/imm32 # compare *(ebp+8) - 73/jump-if-addr>= $write:fake/disp8 - # . . 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 _write/disp32 - # . . discard args - 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp - eb/jump $write:end/disp8 -$write:fake: - # otherwise, treat 'f' as a stream to append to # . save registers 50/push-eax 51/push-ecx @@ -159,4 +133,88 @@ _test-stream: # (stream byte) 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 +== code + +# 3-argument variant of _append +_append-3: # out: (addr byte), outend: (addr byte), s: (addr array byte) -> num_bytes_appended/eax + # . 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 = _append-4(out, outend, &s->data[0], &s->data[s->size]) + # . . push &s->data[s->size] + 8b/copy 1/mod/*+disp8 5/rm32/ebp . . 0/r32/eax 0x10/disp8 . # copy *(ebp+16) to eax + 8b/copy 0/mod/indirect 0/rm32/eax . . . 1/r32/ecx . . # copy *eax to ecx + 8d/copy-address 1/mod/*+disp8 4/rm32/sib 0/base/eax 1/index/ecx . 1/r32/ecx 4/disp8 . # copy eax+ecx+4 to ecx + 51/push-ecx + # . . push &s->data[0] + 8d/copy-address 1/mod/*+disp8 0/rm32/eax . . . 1/r32/ecx 4/disp8 . # copy eax+4 to ecx + 51/push-ecx + # . . push outend + ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 0xc/disp8 . # push *(ebp+12) + # . . push out + ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 8/disp8 . # push *(ebp+8) + # . . call + e8/call _append-4/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0x10/imm32 # add to esp +$_append-3:end: + # . restore registers + 59/pop-to-ecx + # . epilogue + 89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp + 5d/pop-to-ebp + c3/return + +# 4-argument variant of _append +_append-4: # out: (addr byte), outend: (addr byte), in: (addr byte), inend: (addr byte) -> num_bytes_appended/eax: int + # . prologue + 55/push-ebp + 89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp + # . save registers + 51/push-ecx + 52/push-edx + 53/push-ebx + 56/push-esi + 57/push-edi + # num_bytes_appended = 0 + b8/copy-to-eax 0/imm32 + # edi = out + 8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 7/r32/edi 8/disp8 . # copy *(ebp+8) to edi + # edx = outend + 8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 2/r32/edx 0xc/disp8 . # copy *(ebp+12) to edx + # esi = in + 8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 6/r32/esi 0x10/disp8 . # copy *(ebp+16) to esi + # ecx = inend + 8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 1/r32/ecx 0x14/disp8 . # copy *(ebp+20) to ecx +$_append-4:loop: + # if (in >= inend) break + 39/compare 3/mod/direct 6/rm32/esi . . . 1/r32/ecx . . # compare esi with ecx + 73/jump-if-addr>= $_append-4:end/disp8 + # if (out >= outend) abort # just to catch test failures fast + 39/compare 3/mod/direct 7/rm32/edi . . . 2/r32/edx . . # compare edi with edx + 73/jump-if-addr>= $_append-4:end/disp8 # TODO: abort + # *out = *in + 8a/copy-byte 0/mod/indirect 6/rm32/esi . . . 3/r32/BL . . # copy byte at *esi to BL + 88/copy-byte 0/mod/indirect 7/rm32/edi . . . 3/r32/BL . . # copy byte at BL to *edi + # ++num_bytes_appended + 40/increment-eax + # ++in + 46/increment-esi + # ++out + 47/increment-edi + eb/jump $_append-4:loop/disp8 +$_append-4:end: + # . restore registers + 5f/pop-to-edi + 5e/pop-to-esi + 5b/pop-to-ebx + 5a/pop-to-edx + 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 + # . . vim:nowrap:textwidth=0 |