## port of https://github.com/akkartik/crenshaw/blob/master/tutor2.1.pas
# corresponds to the section "single digits" in https://compilers.iecc.com/crenshaw/tutor2.txt
#
# To run:
# $ subx translate apps/crenshaw2.1.subx crenshaw 2.1
# $ echo '3' |subx run apps/crenshaw2.1 |xxd -
# Expected output:
# TODO
#
# The output is the code a function would need to include, returning the
# result in EAX.
#
# Major note: byte strings are not null-terminated. Instead they're prefixed
# with a 32-bit length.
== code
# instruction effective address operand 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
# main:
# abort("Integer")
# push args
68/push "Integer"/imm32
# call
e8/call abort/disp32
# discard arg
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add 4 to ESP
# exit(0)
bb/copy . . . . . . . 0/imm32 # copy 0 to EBX
b8/copy . . . . . . . 1/imm32/exit # copy 1 to EAX
cd/syscall 0x80/imm8
## compiler helpers
# print error message and exit
# really maps to the 'Expected' function in Crenshaw
abort: # s : (address array byte) -> <void>
# error(s)
# push args
ff 6/subop/push 1/mod/*+disp8 4/rm32/sib 4/base/ESP 4/index/none . . 4/disp8 . # push *(ESP+4)
# call
e8/call error/disp32
# discard arg
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add 4 to ESP
# exit(1)
bb/copy . . . . . . . 1/imm32 # copy 1 to EBX
b8/copy . . . . . . . 1/imm32/exit # copy 1 to EAX
cd/syscall 0x80/imm8
# print out "Error: #{s} expected\n" to stderr
error: # s : (address array byte) -> <void>
# write_stderr("Error: ")
# push args
68/push "Error: "/imm32
# call
e8/call write_stderr/disp32
# discard arg
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add 4 to ESP
# write_stderr(s)
# push args
ff 6/subop/push 1/mod/*+disp8 4/rm32/sib 4/base/ESP 4/index/none . . 4/disp8 . # push *(ESP+4)
# call
e8/call write_stderr/disp32
# discard arg
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add 4 to ESP
# write_stderr(" expected")
# push args
68/push " expected"/imm32
# call
e8/call write_stderr/disp32
# discard arg
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add 4 to ESP
# write_stderr("\n")
# push args
68/push Newline/imm32
# call
e8/call write_stderr/disp32
# discard arg
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add 4 to ESP
# end
c3/return
## helpers
# print msg to stderr if a != b, otherwise print "."
check_ints_equal: # (a : int, b : int, msg : (address array byte)) -> boolean
# load args into EAX, EBX and ECX
8b/copy 1/mod/*+disp8 4/rm32/sib 4/base/ESP 4/index/none . 0/r32/EAX 0xc/disp8 . # copy *(ESP+12) to EAX
8b/copy 1/mod/*+disp8 4/rm32/sib 4/base/ESP 4/index/none . 3/r32/EBX 0x8/disp8 . # copy *(ESP+8) to EBX
# if EAX == b/EBX
39/compare 3/mod/direct 0/rm32/EAX . . . 3/r32/EBX . . # compare EAX and EBX
75/jump-if-unequal $check_ints_equal:else/disp8
# print('.')
# push args
68/push "."/imm32
# call
e8/call write_stderr/disp32
# discard arg
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add 4 to ESP
# return
c3/return
# else:
$check_ints_equal:else:
# copy msg into ECX
8b/copy 1/mod/*+disp8 4/rm32/sib 4/base/ESP 4/index/none . 1/r32/ECX 4/disp8 . # copy *(ESP+4) to ECX
# print(ECX)
# push args
51/push-ECX
# call
e8/call write_stderr/disp32
# discard arg
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add 4 to ESP
# print newline
# push args
68/push Newline/imm32
# call
e8/call write_stderr/disp32
# discard arg
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add 4 to ESP
# end
c3/return
# compare a null-terminated ascii string with a more idiomatic length-prefixed byte array
# reason for the name: the only place we should have null-terminated ascii strings is from commandline args
argv_equal: # s : null-terminated ascii string, benchmark : length-prefixed ascii string -> EAX : boolean
# {{{
# pseudocode:
# initialize n = b.length
# initialize s1 = s
# initialize s2 = b.data
# i = 0
# for (i = 0; i < n; ++n)
# c1 = *s1
# c2 = *s2
# if c1 == 0
# return false
# if c1 != c2
# return false
# return *s1 == 0
# initialize s into EDI
8b/copy 1/mod/*+disp8 4/rm32/sib 4/base/ESP 4/index/none . 7/r32/EDI 8/disp8 . # copy *(ESP+8) to EDI
# initialize benchmark length n into EDX
8b/copy 1/mod/*+disp8 4/rm32/sib 4/base/ESP 4/index/none . 2/r32/EDX 4/disp8 . # copy *(ESP+4) to EDX
8b/copy 0/mod/indirect 2/rm32/EDX . . . 2/r32/EDX . . # copy *EDX to EDX
# initialize benchmark data into ESI
8b/copy 1/mod/*+disp8 4/rm32/sib 4/base/ESP 4/index/none . 6/r32/ESI 4/disp8 . # copy *(ESP+4) to ESI
81 0/subop/add 3/mod/direct 6/rm32/ESI . . . . . 4/imm32 # add 4 to ESI
# initialize loop counter i into ECX
b9/copy . . . . . . . 0/imm32/exit # copy 1 to ECX
# while (i/ECX < n/EDX)
$argv_loop:
39/compare 3/mod/direct 1/rm32/ECX . . . 2/r32/EDX . . # compare ECX with EDX
74/jump-if-equal $argv_break/disp8
# c1/EAX, c2/EBX = *s, *benchmark
b8/copy 0/imm32 # clear EAX
8a/copy 0/mod/indirect 7/rm32/EDI . . . 0/r32/EAX . . # copy byte at *EDI to lower byte of EAX
bb/copy 0/imm32 # clear EBX
8a/copy 0/mod/indirect 6/rm32/ESI . . . 3/r32/EBX . . # copy byte at *ESI to lower byte of EBX
# if (c1 == 0) return false
3d/compare . . . . . . . 0/imm32 # compare EAX with 0
74/jump-if-equal $argv_fail/disp8
# if (c1 != c2) return false
39/compare 3/mod/direct 0/rm32/EAX . . . 3/r32/EBX . . # compare EAX with EBX
75/jump-if-not-equal $argv_fail/disp8
# ++s1, ++s2, ++i
41/inc-ECX
46/inc-ESI
47/inc-EDI
# end while
eb/jump $argv_loop/disp8
$argv_break:
# if (*s/EDI == 0) return true
b8/copy 0/imm32 # clear EAX
8a/copy 0/mod/indirect 7/rm32/EDI . . . 0/r32/EAX . . # copy byte at *EDI to lower byte of EAX
81 7/subop/compare 3/mod/direct 0/rm32/EAX . . . . . 0/imm32 # compare EAX with 0
75/jump-if-not-equal $argv_fail/disp8
b8/copy . . . . . . . 1/imm32 # copy 1 to EAX
c3/return
# return false
$argv_fail:
b8/copy . . . . . . . 0/imm32 # copy 0 to EAX
c3/return
# }}}
# tests for argv_equal {{{
test_compare_null_argv_with_empty_array:
# EAX = argv_equal(Null_argv, "")
# push args
68/push Null_argv/imm32
68/push ""/imm32
# call
e8/call argv_equal/disp32
# discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add 8 to ESP
# call check_ints_equal(EAX, 1)
50/push-EAX
68/push 1/imm32/true
68/push "F - test_compare_null_argv_with_empty_array"/imm32
# call
e8/call check_ints_equal/disp32
# discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0xc/imm32 # add 12 to ESP
c3/return
test_compare_null_argv_with_non_empty_array:
# EAX = argv_equal(Null_argv, "Abc")
# push args
68/push Null_argv/imm32
68/push "Abc"/imm32
# call
e8/call argv_equal/disp32
# discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add 8 to ESP
# call check_ints_equal(EAX, 0)
50/push-EAX
68/push 0/imm32/false
68/push "F - test_compare_null_argv_with_non_empty_array"/imm32
# call
e8/call check_ints_equal/disp32
# discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0xc/imm32 # add 12 to ESP
c3/return
test_compare_argv_with_equal_array:
# EAX = argv_equal(Abc_argv, "Abc")
# push args
68/push Abc_argv/imm32
68/push "Abc"/imm32
# call
e8/call argv_equal/disp32
# discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add 8 to ESP
# call check_ints_equal(EAX, 1)
50/push-EAX
68/push 1/imm32/true
68/push "F - test_compare_argv_with_equal_array"/imm32
# call
e8/call check_ints_equal/disp32
# discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0xc/imm32 # add 12 to ESP
c3/return
test_compare_argv_with_inequal_array:
# EAX = argv_equal(Abc_argv, "Adc")
# push args
68/push Abc_argv/imm32
68/push "Adc"/imm32
# call
e8/call argv_equal/disp32
# discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add 8 to ESP
# call check_ints_equal(EAX, 0)
50/push-EAX
68/push 0/imm32/false
68/push "F - test_compare_argv_with_equal_array"/imm32
# call
e8/call check_ints_equal/disp32
# discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0xc/imm32 # add 12 to ESP
c3/return
test_compare_argv_with_empty_array:
# EAX = argv_equal(Abc_argv, "")
# push args
68/push Abc_argv/imm32
68/push ""/imm32
# call
e8/call argv_equal/disp32
# discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add 8 to ESP
# call check_ints_equal(EAX, 0)
50/push-EAX
68/push 0/imm32/false
68/push "F - test_compare_argv_with_equal_array"/imm32
# call
e8/call check_ints_equal/disp32
# discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0xc/imm32 # add 12 to ESP
c3/return
test_compare_argv_with_shorter_array:
# EAX = argv_equal(Abc_argv, "Ab")
# push args
68/push Abc_argv/imm32
68/push "Ab"/imm32
# call
e8/call argv_equal/disp32
# discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add 8 to ESP
# call check_ints_equal(EAX, 0)
50/push-EAX
68/push 0/imm32/false
68/push "F - test_compare_argv_with_shorter_array"/imm32
# call
e8/call check_ints_equal/disp32
# discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0xc/imm32 # add 12 to ESP
c3/return
test_compare_argv_with_longer_array:
# EAX = argv_equal(Abc_argv, "Abcd")
# push args
68/push Abc_argv/imm32
68/push "Abcd"/imm32
# call
e8/call argv_equal/disp32
# discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add 8 to ESP
# call check_ints_equal(EAX, 0)
50/push-EAX
68/push 0/imm32/false
68/push "F - test_compare_argv_with_longer_array"/imm32
# call
e8/call check_ints_equal/disp32
# discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0xc/imm32 # add 12 to ESP
c3/return
# }}}
write_stderr: # s : (address array byte) -> <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
52/push-EDX
53/push-EBX
# write(2/stderr, (data) s+4, (size) *s)
# fd = 2 (stderr)
bb/copy . . . . . . . 2/imm32 # copy 2 to EBX
# x = s+4
8b/copy 1/mod/*+disp8 4/rm32/SIB 5/base/EBP 4/index/none . 1/r32/ECX 8/disp8 . # copy *(EBP+8) to ECX
81 0/subop/add 3/mod/direct 1/rm32/ECX . . . . . 4/imm32 # add 4 to ECX
# size = *s
8b/copy 1/mod/*+disp8 4/rm32/SIB 5/base/EBP 4/index/none . 2/r32/EDX 8/disp8 . # copy *(EBP+8) to EDX
8b/copy 0/mod/indirect 2/rm32/EDX . . . 2/r32/EDX . . # copy *EDX to EDX
# call write()
b8/copy . . . . . . . 4/imm32/write # copy 1 to EAX
cd/syscall 0x80/imm8
# restore registers
5b/pop-EBX
5a/pop-EDX
59/pop-ECX
58/pop-EAX
# end
89/copy 3/mod/direct 4/rm32/ESP . . . 5/r32/EBP . . # copy EBP to ESP
5d/pop-to-EBP
c3/return
write_stdout: # s : (address array byte) -> <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
52/push-EDX
53/push-EBX
# write(1/stdout, (data) s+4, (size) *s)
# fd = 1 (stdout)
bb/copy . . . . . . . 1/imm32 # copy 1 to EBX
# x = s+4
8b/copy 1/mod/*+disp8 4/rm32/SIB 4/base/ESP 4/index/none . 1/r32/ECX 8/disp8 . # copy *(ESP+8) to ECX
81 0/subop/add 3/mod/direct 1/rm32/ECX . . . . . 4/imm32 # add 4 to ECX
# size = *s
8b/copy 1/mod/*+disp8 4/rm32/SIB 4/base/ESP 4/index/none . 2/r32/EDX 8/disp8 . # copy *(ESP+8) to EDX
8b/copy 0/mod/indirect 2/rm32/EDX . . . 2/r32/EDX . . # copy *EDX to EDX
# call write()
b8/copy . . . . . . . 4/imm32/write # copy 1 to EAX
cd/syscall 0x80/imm8
# restore registers
5b/pop-EBX
5a/pop-EDX
59/pop-ECX
58/pop-EAX
# end
89/copy 3/mod/direct 4/rm32/ESP . . . 5/r32/EBP . . # copy EBP to ESP
5d/pop-to-EBP
c3/return
== data
Newline:
# size
01 00 00 00
# data
0a/newline
# for argv_equal tests
Null_argv:
00/null
Abc_argv:
41/A 62/b 63/c 00/null
# vim:ft=subx:nowrap:so=0