4736
We'll use a common stream data structure for input and output streams. Having separate types makes more sense in a more high-level language, where we have type checking and where functions for handling the different types are more concise. But in machine code the sweet spot is more toward fewer types.
This commit is contained in:
Kartik Agaram
parent
3d94e2db0e
commit
f94442fe2d
|
|
@ -1,26 +1,29 @@
|
|||
# write: like _write, but also support in-memory output streams (`ostream`s)
|
||||
# in addition to file descriptors.
|
||||
# write: like _write, but also support in-memory streams in addition to file
|
||||
# descriptors.
|
||||
#
|
||||
# Our first dependency-injected and testable primitive. We can pass it either
|
||||
# a file descriptor or an address to an ostream. If a file descriptor is
|
||||
# passed in, we _write to it using the right syscall. If a 'fake file descriptor'
|
||||
# or ostream is passed in, we append to the ostream. This lets us redirect
|
||||
# output in tests and check it later.
|
||||
# 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.
|
||||
#
|
||||
# An ostream looks like this:
|
||||
# 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 length as usual
|
||||
|
||||
== data
|
||||
|
||||
# In-memory ostream for tests to write() to.
|
||||
# Also illustrates the layout of ostreams.
|
||||
Test-ostream:
|
||||
# In-memory stream for tests to write() to.
|
||||
# Also illustrates the layout of streams.
|
||||
Test-stream:
|
||||
# current write index
|
||||
00 00 00 00
|
||||
# current read index
|
||||
00 00 00 00
|
||||
# length (= 8)
|
||||
08 00 00 00
|
||||
# data
|
||||
|
|
@ -39,7 +42,7 @@ Test-ostream:
|
|||
b8/copy-to-EAX 1/imm32
|
||||
cd/syscall 0x80/imm8
|
||||
|
||||
write: # f : fd or (address ostream), s : (address array byte) -> <void>
|
||||
write: # f : fd or (address stream), s : (address array byte) -> <void>
|
||||
# prolog
|
||||
55/push-EBP
|
||||
89/copy 3/mod/direct 5/rm32/EBP . . . 4/r32/ESP . . # copy ESP to EBP
|
||||
|
|
@ -55,7 +58,7 @@ write: # f : fd or (address ostream), s : (address array byte) -> <void>
|
|||
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 an ostream to append to
|
||||
# otherwise, treat 'f' as an stream to append to
|
||||
# save registers
|
||||
50/push-EAX
|
||||
51/push-ECX
|
||||
|
|
@ -66,15 +69,15 @@ $write:fake:
|
|||
# EDX = f.write
|
||||
8b/copy 0/mod/indirect 1/rm32/ECX . . . 2/r32/EDX . . # copy *ECX to EDX
|
||||
# EBX = f.length
|
||||
8b/copy 1/mod/*+disp8 1/rm32/ECX . . . 3/r32/EBX 4/disp8 . # copy *(ECX+4) to EBX
|
||||
8b/copy 1/mod/*+disp8 1/rm32/ECX . . . 3/r32/EBX 8/disp8 . # copy *(ECX+8) to EBX
|
||||
# EAX = _append(&f.data[f.write], &f.data[f.length], s)
|
||||
# push s
|
||||
ff 6/subop/push 1/mod/*+disp8 4/rm32/sib 5/base/EBP 4/index/none . . 0xc/disp8 . # push *(EBP+12)
|
||||
# push &f.data[f.length]
|
||||
8d/copy-address 1/mod/*+disp8 4/rm32/sib 1/base/ECX 3/index/EBX . 3/r32/EBX 8/disp8 . # copy ECX+EBX+8 to EBX
|
||||
8d/copy-address 1/mod/*+disp8 4/rm32/sib 1/base/ECX 3/index/EBX . 3/r32/EBX 0xc/disp8 . # copy ECX+EBX+12 to EBX
|
||||
53/push-EBX
|
||||
# push &f.data[f.write]
|
||||
8d/copy-address 1/mod/*+disp8 4/rm32/sib 1/base/ECX 2/index/EDX . 3/r32/EBX 8/disp8 . # copy ECX+EBX+8 to EBX
|
||||
8d/copy-address 1/mod/*+disp8 4/rm32/sib 1/base/ECX 2/index/EDX . 3/r32/EBX 0xc/disp8 . # copy ECX+EDX+12 to EBX
|
||||
53/push-EBX
|
||||
# call
|
||||
e8/call _append/disp32
|
||||
|
|
@ -93,7 +96,7 @@ $write:end:
|
|||
5d/pop-to-EBP
|
||||
c3/return
|
||||
|
||||
clear-ostream: # f : (address ostream)
|
||||
clear-stream: # f : (address stream)
|
||||
# prolog
|
||||
55/push-EBP
|
||||
89/copy 3/mod/direct 5/rm32/EBP . . . 4/r32/ESP . . # copy ESP to EBP
|
||||
|
|
@ -103,24 +106,26 @@ clear-ostream: # f : (address ostream)
|
|||
# EAX = f
|
||||
8b/copy 1/mod/*+disp8 4/rm32/sib 5/base/EBP 4/index/none 0/r32/EAX 8/disp8 . # copy *(EBP+8) to EAX
|
||||
# ECX = f.length
|
||||
8b/copy 1/mod/*+disp8 0/rm32/EAX . . . 1/r32/ECX 4/disp8 . # copy *(EAX+4) to ECX
|
||||
8b/copy 1/mod/*+disp8 0/rm32/EAX . . . 1/r32/ECX 8/disp8 . # copy *(EAX+8) to ECX
|
||||
# ECX = &f.data[f.length]
|
||||
8d/copy-address 1/mod/*+disp8 4/rm32/sib 0/base/EAX 1/index/ECX . 1/r32/ECX 8/disp8 . # copy EAX+ECX+8 to ECX
|
||||
8d/copy-address 1/mod/*+disp8 4/rm32/sib 0/base/EAX 1/index/ECX . 1/r32/ECX 0xc/disp8 . # copy EAX+ECX+12 to ECX
|
||||
# f.write = 0
|
||||
c7/copy 0/mod/direct 0/rm32/EAX . . . . . 0/imm32 # copy to *EAX
|
||||
# f.read = 0
|
||||
c7/copy 1/mod/*+disp8 0/rm32/EAX . . . . 4/disp8 0/imm32 # copy to *(EAX+4)
|
||||
# EAX = f.data
|
||||
81 0/subop/add 3/mod/direct 0/rm32/EAX . . . . . 8/imm32 # add to EAX
|
||||
81 0/subop/add 3/mod/direct 0/rm32/EAX . . . . . 0xc/imm32 # add to EAX
|
||||
# while (true)
|
||||
$clear-ostream:loop:
|
||||
$clear-stream:loop:
|
||||
# if EAX >= ECX break
|
||||
39/compare 3/mod/direct 0/rm32/EAX . . . 1/r32/ECX . . # compare EAX with ECX
|
||||
7d/jump-if-greater-or-equal $clear-ostream:end/disp8
|
||||
7d/jump-if-greater-or-equal $clear-stream:end/disp8
|
||||
# *EAX = 0
|
||||
c7/copy 0/mod/direct 0/rm32/EAX . . . . . 0/imm32 # copy to *EAX
|
||||
# EAX += 4
|
||||
81 0/subop/add 3/mod/direct 0/rm32/EAX . . . . . 4/imm32 # add to EAX
|
||||
eb/jump $clear-ostream:loop/disp8
|
||||
$clear-ostream:end:
|
||||
eb/jump $clear-stream:loop/disp8
|
||||
$clear-stream:end:
|
||||
# restore registers
|
||||
59/pop-to-ECX
|
||||
58/pop-to-EAX
|
||||
|
|
@ -130,28 +135,28 @@ $clear-ostream:end:
|
|||
c3/return
|
||||
|
||||
test-write-single:
|
||||
# clear-ostream(Test-ostream)
|
||||
# clear-stream(Test-stream)
|
||||
# push args
|
||||
68/push Test-ostream/imm32
|
||||
68/push Test-stream/imm32
|
||||
# call
|
||||
e8/call clear-ostream/disp32
|
||||
e8/call clear-stream/disp32
|
||||
# discard args
|
||||
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP
|
||||
# write(Test-ostream, "Ab")
|
||||
# write(Test-stream, "Ab")
|
||||
# push args
|
||||
68/push "Ab"/imm32
|
||||
68/push Test-ostream/imm32
|
||||
68/push Test-stream/imm32
|
||||
# call
|
||||
e8/call write/disp32
|
||||
# discard args
|
||||
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP
|
||||
# check-ints-equal(*Test-ostream.data, 41/A 62/b 00 00, msg)
|
||||
# check-ints-equal(*Test-stream.data, 41/A 62/b 00 00, msg)
|
||||
# push args
|
||||
68/push "F - test-write-single"/imm32
|
||||
68/push 0x006241/imm32/Ab
|
||||
# push *Test-ostream.data
|
||||
b8/copy-to-EAX Test-ostream/imm32
|
||||
ff 6/subop/push 1/mod/*+disp8 0/rm32/EAX . . . . 8/disp8 . # push *(EAX+8)
|
||||
# push *Test-stream.data
|
||||
b8/copy-to-EAX Test-stream/imm32
|
||||
ff 6/subop/push 1/mod/*+disp8 0/rm32/EAX . . . . 0xc/disp8 . # push *(EAX+12)
|
||||
# call
|
||||
e8/call check-ints-equal/disp32
|
||||
# discard args
|
||||
|
|
@ -160,36 +165,36 @@ test-write-single:
|
|||
c3/return
|
||||
|
||||
test-write-appends:
|
||||
# clear-ostream(Test-ostream)
|
||||
# clear-stream(Test-stream)
|
||||
# push args
|
||||
68/push Test-ostream/imm32
|
||||
68/push Test-stream/imm32
|
||||
# call
|
||||
e8/call clear-ostream/disp32
|
||||
e8/call clear-stream/disp32
|
||||
# discard args
|
||||
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP
|
||||
# write(Test-ostream, "C")
|
||||
# write(Test-stream, "C")
|
||||
# push args
|
||||
68/push "C"/imm32
|
||||
68/push Test-ostream/imm32
|
||||
68/push Test-stream/imm32
|
||||
# call
|
||||
e8/call write/disp32
|
||||
# discard args
|
||||
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP
|
||||
# write(Test-ostream, "D")
|
||||
# write(Test-stream, "D")
|
||||
# push args
|
||||
68/push "D"/imm32
|
||||
68/push Test-ostream/imm32
|
||||
68/push Test-stream/imm32
|
||||
# call
|
||||
e8/call write/disp32
|
||||
# discard args
|
||||
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP
|
||||
# check-ints-equal(*Test-ostream.data, 43/C 44/D 00 00, msg)
|
||||
# check-ints-equal(*Test-stream.data, 43/C 44/D 00 00, msg)
|
||||
# push args
|
||||
68/push "F - test-write-appends"/imm32
|
||||
68/push 0x00004443/imm32/C-D
|
||||
# push *Test-ostream.data
|
||||
b8/copy-to-EAX Test-ostream/imm32
|
||||
ff 6/subop/push 1/mod/*+disp8 0/rm32/EAX . . . . 8/disp8 . # push *(EAX+8)
|
||||
# push *Test-stream.data
|
||||
b8/copy-to-EAX Test-stream/imm32
|
||||
ff 6/subop/push 1/mod/*+disp8 0/rm32/EAX . . . . 0xc/disp8 . # push *(EAX+12)
|
||||
# call
|
||||
e8/call check-ints-equal/disp32
|
||||
# discard args
|
||||
|
|
|
|||
Binary file not shown.
Binary file not shown.
Loading…
Reference in New Issue