# primitives for emitting traces to a 'trace' stream, and for tests to make assertions on its contents
#
# A trace stream looks like a regular stream:
# write : int # index at which writes go
# read : int # index that we've read until
# data : (array byte) # prefixed by length as usual
# Usually the trace stream will be in a separate segment set aside for the purpose.
#
# primitives for operating on traces (arguments in quotes):
# - initialize-trace-stream: populates Trace-stream with a new segment of the given 'size'
# - trace: adds a 'line' to Trace-stream
# - check-trace-contains: scans from Trace-stream's start for a matching 'line', prints a 'message' to stderr on failure
# - check-trace-scans-to: scans from Trace-stream's read pointer for a matching 'line', prints a 'message' to stderr on failure
== data
# We'll save the address of the trace segment here.
Trace-stream:
0/imm32
Trace-segment:
0/imm32/curr
0/imm32/end
# Fake trace-stream for tests.
# Also illustrates the layout of the real trace-stream (segment).
_test-trace-stream:
# current write index
0/imm32
# current read index
0/imm32
# length
8/imm32
# data
00 00 00 00 00 00 00 00 # 8 bytes
== 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
#? Entry: # run a single test, while debugging
#? e8/call test-trace-single/disp32
#? # 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
#? b8/copy-to-EAX 1/imm32/exit
#? cd/syscall 0x80/imm8
# Allocate a new segment for the trace stream, initialize its length, and save its address to Trace-stream.
# The Trace-stream segment will consist of variable-length lines separated by newlines (0x0a)
initialize-trace-stream: # n : int -> <void>
# . prolog
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 = n
8b/copy 1/mod/*+disp8 5/rm32/EBP . . . 1/r32/ECX 8/disp8 . # copy *(EBP+8) to ECX
# Trace-segment = new-segment(n)
# . . push args
68/push Trace-segment/imm32
51/push-ECX
# . . call
e8/call new-segment/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP
# copy Trace-segment->curr to *Trace-stream
8b/copy 0/mod/indirect 5/rm32/.disp32 . . 0/r32/EAX Trace-segment/disp32 # copy *Trace-segment to EAX
89/copy 0/mod/indirect 5/rm32/.disp32 . . 0/r32/EAX Trace-stream/disp32 # copy EAX to *Trace-stream
# Trace-stream->length = n - 12
# . ECX -= 12
81 5/subop/subtract 3/mod/direct 1/rm32/ECX . . . . . 0xc/imm32 # subtract from ECX
# . Trace-stream->length = ECX
89/copy 1/mod/*+disp8 0/rm32/EAX . . . 1/r32/ECX 8/disp8 . # copy ECX to *(EAX+8)
$initialize-trace-stream:end:
# . restore registers
59/pop-to-ECX
58/pop-to-EAX
# . epilog
89/copy 3/mod/direct 4/rm32/ESP . . . 5/r32/EBP . . # copy EBP to ESP
5d/pop-to-EBP
c3/return
# Append a string to the given trace stream.
# Silently give up if it's already full. Or truncate the string if there isn't enough room.
trace: # line : string
# . prolog
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
# EDI = *Trace-stream
8b/copy 0/mod/indirect 5/rm32/.disp32 . . 7/r32/EDI Trace-stream/disp32 # copy *Trace-stream to EDI
# ESI = line
8b/copy 1/mod/*+disp8 5/rm32/EBP . . 6/r32/ESI 8/disp8 . # copy *(EBP+8) to ESI
# ECX = t->write
8b/copy 0/mod/indirect 7/rm32/EDI . . . 1/r32/ECX . . # copy *EDI to ECX
# EDX = t->length
8b/copy 1/mod/*+disp8 7/rm32/EDI . . . 2/r32/EDX 8/disp8 . # copy *(EDI+8) to EDX
# EAX = _append-3(&t->data[t->write], &t->data[t->length], line)
# . . push line
56/push-ESI
# . . push &t->data[t->length]
8d/copy-address 1/mod/*+disp8 4/rm32/sib 7/base/EDI 2/index/EDX . 3/r32/EBX 0xc/disp8 . # copy EDI+EDX+12 to EBX
53/push-EBX
# . . push &t->data[t->write]
8d/copy-address 1/mod/*+disp8 4/rm32/sib 7/base/EDI 1/index/ECX . 3/r32/EBX 0xc/disp8 . # copy EDI+ECX+12 to EBX
53/push-EBX
# . . call
e8/call _append-3/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0xc/imm32 # add to ESP
# if (EAX == 0) return
3d/compare-EAX-and 0/imm32
74/jump-if-equal $trace:end/disp8
# t->write += EAX
01/add 0/mod/indirect 7/rm32/EDI . . . 0/r32/EAX . . # add EAX to *EDI
# refresh ECX = t->write
8b/copy 0/mod/indirect 7/rm32/EDI . . . 1/r32/ECX . . # copy *EDI to ECX
# EAX = _append-3(&t->data[t->write], &t->data[t->length], line)
# . . push line
68/push Newline/imm32
# . . push &t->data[t->length]
8d/copy-address 1/mod/*+disp8 4/rm32/sib 7/base/EDI 2/index/EDX . 3/r32/EBX 0xc/disp8 . # copy EDI+EDX+12 to EBX
53/push-EBX
# . . push &t->data[t->write]
8d/copy-address 1/mod/*+disp8 4/rm32/sib 7/base/EDI 1/index/ECX . 3/r32/EBX 0xc/disp8 . # copy EDI+ECX+12 to EBX
53/push-EBX
# . . call
e8/call _append-3/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0xc/imm32 # add to ESP
# t->write += EAX
01/add 0/mod/indirect 7/rm32/EDI . . . 0/r32/EAX . . # add EAX to *EDI
$trace: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
# . epilog
89/copy 3/mod/direct 4/rm32/ESP . . . 5/r32/EBP . . # copy EBP to ESP
5d/pop-to-EBP
c3/return
test-trace-single:
# *Trace-stream = _test-trace-stream
b8/copy-to-EAX _test-trace-stream/imm32
89/copy 0/mod/indirect 5/rm32/.disp32 . . 0/r32/EAX Trace-stream/disp32 # copy EAX to *Trace-stream
# clear-trace-stream()
e8/call clear-trace-stream/disp32
# trace("Ab")
# . . push args
68/push "Ab"/imm32
# . . call
e8/call trace/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP
# check-ints-equal(*_test-trace-stream->data, 41/A 62/b 0a/newline 00, msg)
# . . push args
68/push "F - test-trace-single"/imm32
68/push 0x0a6241/imm32/Ab-newline
# . . push *_test-trace-stream->data
b8/copy-to-EAX _test-trace-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
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0xc/imm32 # add to ESP
# end
c3/return
test-trace-appends:
# *Trace-stream = _test-trace-stream
b8/copy-to-EAX _test-trace-stream/imm32
89/copy 0/mod/indirect 5/rm32/.disp32 . . 0/r32/EAX Trace-stream/disp32 # copy EAX to *Trace-stream
# clear-trace-stream()
e8/call clear-trace-stream/disp32
# trace("C")
# . . push args
68/push "C"/imm32
# . . call
e8/call trace/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP
# trace("D")
# . . push args
68/push "D"/imm32
# . . call
e8/call trace/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP
# check-ints-equal(*_test-trace-stream->data, 43/C 0a/newline 44/D 0a/newline, msg)
# . . push args
68/push "F - test-trace-appends"/imm32
68/push 0x0a440a43/imm32/C-newline-D-newline
# . . push *_test-trace-stream->data
b8/copy-to-EAX _test-trace-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
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0xc/imm32 # add to ESP
# end
c3/return
test-trace-empty-line:
# *Trace-stream = _test-trace-stream
b8/copy-to-EAX _test-trace-stream/imm32
89/copy 0/mod/indirect 5/rm32/.disp32 . . 0/r32/EAX Trace-stream/disp32 # copy EAX to *Trace-stream
# clear-trace-stream()
e8/call clear-trace-stream/disp32
# trace("")
# . . push args
68/push ""/imm32
# . . call
e8/call trace/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP
# check-ints-equal(*_test-trace-stream->data, 0, msg)
# . . push args
68/push "F - test-trace-empty-line"/imm32
68/push 0/imm32
# . . push *_test-trace-stream->data
b8/copy-to-EAX _test-trace-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
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0xc/imm32 # add to ESP
# end
c3/return
check-trace-contains: # line : (address string), msg : (address string)
# . prolog
55/push-EBP
89/copy 3/mod/direct 5/rm32/EBP . . . 4/r32/ESP . . # copy ESP to EBP
# rewind-stream(*Trace-stream)
# . . push args
ff 6/subop/push 0/mod/indirect 5/rm32/.disp32 . . . Trace-stream/disp32 # push *Segment-size
# . . call
e8/call rewind-stream/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP
# check-trace-can-scan-to(line, msg)
# . . 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 check-trace-can-scan-to/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP
$check-trace-contains:end:
# . epilog
89/copy 3/mod/direct 4/rm32/ESP . . . 5/r32/EBP . . # copy EBP to ESP
5d/pop-to-EBP
c3/return
check-trace-scans-to: # line : (address string), msg : (address string)
# . prolog
55/push-EBP
89/copy 3/mod/direct 5/rm32/EBP . . . 4/r32/ESP . . # copy ESP to EBP
# . save registers
50/push-EAX
# EAX = trace-scan(*Trace-stream, line)
# . . push args
ff 6/subop/push 1/mod/*+disp8 5/rm32/EBP . . . . 8/disp8 . # push *(EBP+8)
ff 6/subop/push 0/mod/indirect 5/rm32/.disp32 . . . Trace-stream/disp32 # push *Segment-size
# . . call
e8/call check-trace-can-scan-to/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP
# check-ints-equal(EAX, 1, msg)
# . . push args
ff 6/subop/push 1/mod/*+disp8 5/rm32/EBP . . . . 0xc/disp8 . # push *(EBP+12)
68/push 1/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
$check-trace-scans-to:end:
# . restore registers
58/pop-to-EAX
# . epilog
89/copy 3/mod/direct 4/rm32/ESP . . . 5/r32/EBP . . # copy EBP to ESP
5d/pop-to-EBP
c3/return
# Start scanning from Trace-stream->read for 'line'. If found, update Trace-stream->read and return true.
trace-scan: # line : string -> result/EAX : boolean
# pseudocode:
# while true:
# if Trace-stream->read >= Trace-stream->write
# break
# if next-line-matches?(Trace-stream, line)
# skip-next-line(Trace-stream)
# return true
# return false
#
# . prolog
55/push-EBP
89/copy 3/mod/direct 5/rm32/EBP . . . 4/r32/ESP . . # copy ESP to EBP
# . save registers
51/push-ECX
56/push-ESI
# ESI = *Trace-stream
8b/copy 0/mod/indirect 5/rm32/.disp32 . . 6/r32/ESI Trace-stream/disp32 # copy *Trace-stream to ESI
# ECX = Trace-stream->write
$trace-scan:loop:
# if (Trace-stream->read >= Trace-stream->write) return false
39/compare 1/mod/*+disp8 6/rm32/ESI . . . 1/r32/ECX 4/disp8 . # compare ECX with *(ESI+4)
7d/jump-if-greater-or-equal $trace-scan:false/disp8
# EAX = next-line-matches?(Trace-stream, line)
# . . push args
ff 6/subop/push 1/mod/*+disp8 5/rm32/EBP . . . . 8/disp8 . # push *(EBP+8)
56/push-ESI
# . . call
e8/call next-line-matches?/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP
# if (EAX == 0) continue
3d/compare-EAX-and 0/imm32
74/jump-if-equal $trace-scan:loop/disp8
$trace-scan:true:
# skip-next-line(Trace-stream)
# . . push args
56/push-ESI
# . . call
e8/call skip-next-line/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP
# return true
b8/copy-to-EAX 1/imm32/true
eb/jump $trace-scan:end/disp8
$trace-scan:false:
b8/copy-to-EAX 0/imm32/false
$trace-scan:end:
# . 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
next-line-matches?: # t : (address stream), line : string -> result/EAX : boolean
# pseudocode:
# while true:
# if (currl >= maxl) break
# if (currt >= maxt) return false
# if (*currt != *currl) return false
# ++currt
# ++currl
# return *currt == '\n'
#
# . prolog
55/push-EBP
89/copy 3/mod/direct 5/rm32/EBP . . . 4/r32/ESP . . # copy ESP to EBP
# . save registers
# ESI = line
# maxl/ECX = line->data + line->size
# currl/ESI = line->data
# EDI = t
# maxt/EDX = t->data + t->write
# currt/EDI = t->data + t->read
$next-line-matches?:loop:
# if (currl >= maxl) break
# if (currt >= maxt) return false
# if (*currt != *currl) return false
# ++currt
# ++currl
$next-line-matches?:break:
# return *currt == '\n'
$next-line-matches?:end:
# . restore registers
# . epilog
89/copy 3/mod/direct 4/rm32/ESP . . . 5/r32/EBP . . # copy EBP to ESP
5d/pop-to-EBP
c3/return
skip-next-line: # t : (address stream)
# pseudocode:
# i = t->read
# curr = t->data + t->read
# max = t->data + t->write
# while true
# if (curr >= max) break
# if (*curr == '\n') break
# ++curr
# ++i
# t->read = i
#
# . prolog
55/push-EBP
89/copy 3/mod/direct 5/rm32/EBP . . . 4/r32/ESP . . # copy ESP to EBP
# . save registers
# i = t->read
# curr = t->data + t->read
# max = t->data + t->write
$skip-next-line:loop:
# if (curr >= max) break
# if (*curr == '\n') break
# ++curr
# ++i
$skip-next-line:end:
# t->read = i
# . restore registers
# . epilog
89/copy 3/mod/direct 4/rm32/ESP . . . 5/r32/EBP . . # copy EBP to ESP
5d/pop-to-EBP
c3/return
test-trace-scan-first:
# setup
# . *Trace-stream = _test-trace-stream
b8/copy-to-EAX _test-trace-stream/imm32
89/copy 0/mod/indirect 5/rm32/.disp32 . . 0/r32/EAX Trace-stream/disp32 # copy EAX to *Trace-stream
# . clear-trace-stream()
e8/call clear-trace-stream/disp32
# . trace("Ab")
# . . push args
68/push "Ab"/imm32
# . . call
e8/call trace/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP
# EAX = trace-scan("Ab")
# . . push args
68/push "Ab"/imm32
# . . call
e8/call trace-scan/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP
# check-ints-equal(EAX, 1, msg)
# . . push args
68/push "F - test-trace-scan-first"/imm32
68/push 1/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
# . end
c3/return
test-trace-scan-skips-lines-until-found:
# setup
# . *Trace-stream = _test-trace-stream
b8/copy-to-EAX _test-trace-stream/imm32
89/copy 0/mod/indirect 5/rm32/.disp32 . . 0/r32/EAX Trace-stream/disp32 # copy EAX to *Trace-stream
# . clear-trace-stream()
e8/call clear-trace-stream/disp32
# . trace("Ab")
# . . push args
68/push "Ab"/imm32
# . . call
e8/call trace/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP
# . trace("cd")
# . . push args
68/push "cd"/imm32
# . . call
e8/call trace/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP
# EAX = trace-scan("cd")
# . . push args
68/push "cd"/imm32
# . . call
e8/call trace-scan/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP
# check-ints-equal(EAX, 1, msg)
# . . push args
68/push "F - test-trace-scan-skips-lines-until-found"/imm32
68/push 1/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
# . end
c3/return
test-trace-second-scan-starts-where-first-left-off:
# setup
# . *Trace-stream = _test-trace-stream
b8/copy-to-EAX _test-trace-stream/imm32
89/copy 0/mod/indirect 5/rm32/.disp32 . . 0/r32/EAX Trace-stream/disp32 # copy EAX to *Trace-stream
# . clear-trace-stream()
e8/call clear-trace-stream/disp32
# . trace("Ab")
# . . push args
68/push "Ab"/imm32
# . . call
e8/call trace/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP
# . EAX = trace-scan("Ab")
# . . push args
68/push "Ab"/imm32
# . . call
e8/call trace-scan/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP
# second scan fails
# . EAX = trace-scan("Ab")
# . . push args
68/push "Ab"/imm32
# . . call
e8/call trace-scan/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP
# check-ints-equal(EAX, 0, msg)
# . . push args
68/push "F - test-trace-second-scan-starts-where-first-left-off"/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
# . end
c3/return
test-trace-scan-failure-leaves-read-index-untouched:
# setup
# . *Trace-stream = _test-trace-stream
b8/copy-to-EAX _test-trace-stream/imm32
89/copy 0/mod/indirect 5/rm32/.disp32 . . 0/r32/EAX Trace-stream/disp32 # copy EAX to *Trace-stream
# . clear-trace-stream()
e8/call clear-trace-stream/disp32
# . trace("Ab")
# . . push args
68/push "Ab"/imm32
# . . call
e8/call trace/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP
# . check-ints-equal(_test-trace-stream->read, 0, msg)
# . . push args
68/push "F - test-trace-second-scan-starts-where-first-left-off/precondition-failure"/imm32
68/push 0/imm32
b8/copy-to-EAX _test-trace-stream/imm32
ff 6/subop/push 1/mod/*+disp8 0/rm32/EAX . . . . 4/disp8 . # push *(EAX+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
# perform a failing scan
# . EAX = trace-scan("Ax")
# . . push args
68/push "Ax"/imm32
# . . call
e8/call trace-scan/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP
# no change in read index
# . check-ints-equal(_test-trace-stream->read, 0, msg)
# . . push args
68/push "F - test-trace-second-scan-starts-where-first-left-off"/imm32
68/push 0/imm32
b8/copy-to-EAX _test-trace-stream/imm32
ff 6/subop/push 1/mod/*+disp8 0/rm32/EAX . . . . 4/disp8 . # push *(EAX+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
# . end
c3/return
clear-trace-stream:
# . prolog
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
# EAX = *Trace-stream
8b/copy 0/mod/indirect 5/rm32/.disp32 . . 0/r32/EAX Trace-stream/disp32 # copy *Trace-stream to EAX
# ECX = t->length
8b/copy 1/mod/*+disp8 0/rm32/EAX . . . 1/r32/ECX 8/disp8 . # copy *(EAX+8) to ECX
# ECX = &t->data[t->length]
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
# t->write = 0
c7 0/subop/copy 0/mod/direct 0/rm32/EAX . . . . . 0/imm32 # copy to *EAX
# t->read = 0
c7 0/subop/copy 1/mod/*+disp8 0/rm32/EAX . . . . 4/disp8 0/imm32 # copy to *(EAX+4)
# EAX = t->data
81 0/subop/add 3/mod/direct 0/rm32/EAX . . . . . 0xc/imm32 # add to EAX
$clear-trace-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-trace-stream:end/disp8
# *EAX = 0
c7 0/subop/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-trace-stream:loop/disp8
$clear-trace-stream:end:
# . restore registers
59/pop-to-ECX
58/pop-to-EAX
# . epilog
89/copy 3/mod/direct 4/rm32/ESP . . . 5/r32/EBP . . # copy EBP to ESP
5d/pop-to-EBP
c3/return
# - helpers
# 3-argument variant of _append
_append-3: # out : address, outend : address, s : (array byte) -> num_bytes_appended/EAX
# . 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 = _append-4(out, outend, &s->data[0], &s->data[s->length])
# . . push &s->data[s->length]
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
# . epilog
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 : address, outend : address, in : address, inend : address -> num_bytes_appended/EAX
# . prolog
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
# EAX/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
7d/jump-if-greater-or-equal $_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
7d/jump-if-greater-or-equal $_append-4:abort/disp8
# *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
# . epilog
89/copy 3/mod/direct 4/rm32/ESP . . . 5/r32/EBP . . # copy EBP to ESP
5d/pop-to-EBP
c3/return
$_append-4:abort:
# . _write(2/stderr, error)
# . . push args
68/push "stream overflow"/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