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Diffstat (limited to 'subx/examples/ex11.subx')
| -rw-r--r-- | subx/examples/ex11.subx | 357 |
1 files changed, 0 insertions, 357 deletions
diff --git a/subx/examples/ex11.subx b/subx/examples/ex11.subx deleted file mode 100644 index ba75c1d3..00000000 --- a/subx/examples/ex11.subx +++ /dev/null @@ -1,357 +0,0 @@ -# Null-terminated vs length-prefixed ascii strings. -# -# By default we create strings with a 4-byte length prefix rather than a null suffix. -# However we still need null-prefixed strings when interacting with the Linux -# kernel in a few places. This layer implements a function for comparing -# a null-terminated 'kernel string' with a length-prefixed 'SubX string'. -# -# To run (from the subx directory): -# $ ./subx translate examples/ex11.subx -o examples/ex11 -# $ ./subx run examples/ex11 # runs a series of tests -# ...... # all tests pass -# -# (We can't yet run the tests when given a "test" commandline argument, -# because checking for it would require the function being tested! Breakage -# would cause tests to not run, rather than to fail as we'd like.) - -== code 0x09000000 -# 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 all tests - e8/call run-tests/disp32 # 'run-tests' is a function created automatically by SubX. It calls all functions that start with 'test-'. - # syscall(exit, EAX) - 89/copy 3/mod/direct 3/rm32/EBX . . . 0/r32/EAX . . # copy EAX to EBX - b8/copy-to-EAX 1/imm32/exit - cd/syscall 0x80/imm8 - -# 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 -kernel-string-equal?: # s : null-terminated ascii string, benchmark : length-prefixed ascii string -> EAX : boolean - # pseudocode: - # n = benchmark->length - # s1 = s - # s2 = benchmark->data - # i = 0 - # while i < n - # c1 = *s1 - # c2 = *s2 - # if (c1 == 0) return false - # if (c1 != c2) return false - # ++s1, ++s2, ++i - # return *s1 == 0 - # - # registers: - # i: ECX - # n: EDX - # s1: EDI - # s2: ESI - # c1: EAX - # c2: EBX - # - # . 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 - # s1/EDI = s - 8b/copy 1/mod/*+disp8 5/rm32/EBP . . . 7/r32/EDI 8/disp8 . # copy *(EBP+8) to EDI - # n/EDX = benchmark->length - 8b/copy 1/mod/*+disp8 5/rm32/EBP . . . 2/r32/EDX 0xc/disp8 . # copy *(EBP+12) to EDX - 8b/copy 0/mod/indirect 2/rm32/EDX . . . 2/r32/EDX . . # copy *EDX to EDX - # s2/ESI = benchmark->data - 8b/copy 1/mod/*+disp8 5/rm32/EBP . . . 6/r32/ESI 0xc/disp8 . # copy *(EBP+12) to ESI - 81 0/subop/add 3/mod/direct 6/rm32/ESI . . . . . 4/imm32 # add to ESI - # i/ECX = c1/EAX = c2/EBX = 0 - b9/copy-to-ECX 0/imm32/exit - b8/copy-to-EAX 0/imm32 - bb/copy-to-EBX 0/imm32 -$kernel-string-equal?:loop: - # if (i >= n) break - 39/compare 3/mod/direct 1/rm32/ECX . . . 2/r32/EDX . . # compare ECX with EDX - 7d/jump-if-greater-or-equal $kernel-string-equal?:break/disp8 - # c1 = *s1 - 8a/copy-byte 0/mod/indirect 7/rm32/EDI . . . 0/r32/AL . . # copy byte at *EDI to AL - # c2 = *s2 - 8a/copy-byte 0/mod/indirect 6/rm32/ESI . . . 3/r32/BL . . # copy byte at *ESI to BL - # if (c1 == 0) return false - 3d/compare-EAX-and 0/imm32 - 74/jump-if-equal $kernel-string-equal?:false/disp8 - # if (c1 != c2) return false - 39/compare 3/mod/direct 0/rm32/EAX . . . 3/r32/EBX . . # compare EAX and EBX - 75/jump-if-not-equal $kernel-string-equal?:false/disp8 - # ++i - 41/increment-ECX - # ++s1 - 47/increment-EDI - # ++s2 - 46/increment-ESI - eb/jump $kernel-string-equal?:loop/disp8 -$kernel-string-equal?:break: - # return *s1 == 0 - 8a/copy-byte 0/mod/indirect 7/rm32/EDI . . . 0/r32/AL . . # copy byte at *EDI to AL - 3d/compare-EAX-and 0/imm32 - 75/jump-if-not-equal $kernel-string-equal?:false/disp8 -$kernel-string-equal?:true: - b8/copy-to-EAX 1/imm32 - eb/jump $kernel-string-equal?:end/disp8 -$kernel-string-equal?:false: - b8/copy-to-EAX 0/imm32 -$kernel-string-equal?: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 - -# - tests - -test-compare-null-kernel-string-with-empty-array: - # EAX = kernel-string-equal?(Null-kernel-string, "") - # . . push args - 68/push ""/imm32 - 68/push Null-kernel-string/imm32 - # . . call - e8/call kernel-string-equal?/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 - 68/push "F - test-compare-null-kernel-string-with-empty-array"/imm32 - 68/push 1/imm32/true - 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 - c3/return - -test-compare-null-kernel-string-with-non-empty-array: - # EAX = kernel-string-equal?(Null-kernel-string, "Abc") - # . . push args - 68/push "Abc"/imm32 - 68/push Null-kernel-string/imm32 - # . . call - e8/call kernel-string-equal?/disp32 - # . . discard args - 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP - # check-ints-equal(EAX, 0, msg) - # . . push args - 68/push "F - test-compare-null-kernel-string-with-non-empty-array"/imm32 - 68/push 0/imm32/false - 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 - c3/return - -test-compare-kernel-string-with-equal-array: - # EAX = kernel-string-equal?(_test-Abc-kernel-string, "Abc") - # . . push args - 68/push "Abc"/imm32 - 68/push _test-Abc-kernel-string/imm32 - # . . call - e8/call kernel-string-equal?/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 - 68/push "F - test-compare-kernel-string-with-equal-array"/imm32 - 68/push 1/imm32/true - 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 - c3/return - -test-compare-kernel-string-with-inequal-array: - # EAX = kernel-string-equal?(_test-Abc-kernel-string, "Adc") - # . . push args - 68/push "Adc"/imm32 - 68/push _test-Abc-kernel-string/imm32 - # . . call - e8/call kernel-string-equal?/disp32 - # . . discard args - 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP - # check-ints-equal(EAX, 0, msg) - # . . push args - 68/push "F - test-compare-kernel-string-with-equal-array"/imm32 - 68/push 0/imm32/false - 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 - c3/return - -test-compare-kernel-string-with-empty-array: - # EAX = kernel-string-equal?(_test-Abc-kernel-string, "") - # . . push args - 68/push ""/imm32 - 68/push _test-Abc-kernel-string/imm32 - # . . call - e8/call kernel-string-equal?/disp32 - # . . discard args - 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP - # check-ints-equal(EAX, 0, msg) - # . . push args - 68/push "F - test-compare-kernel-string-with-equal-array"/imm32 - 68/push 0/imm32/false - 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 - c3/return - -test-compare-kernel-string-with-shorter-array: - # EAX = kernel-string-equal?(_test-Abc-kernel-string, "Ab") - # . . push args - 68/push "Ab"/imm32 - 68/push _test-Abc-kernel-string/imm32 - # . . call - e8/call kernel-string-equal?/disp32 - # . . discard args - 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP - # check-ints-equal(EAX, 0, msg) - # . . push args - 68/push "F - test-compare-kernel-string-with-shorter-array"/imm32 - 68/push 0/imm32/false - 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 - c3/return - -test-compare-kernel-string-with-longer-array: - # EAX = kernel-string-equal?(_test-Abc-kernel-string, "Abcd") - # . . push args - 68/push "Abcd"/imm32 - 68/push _test-Abc-kernel-string/imm32 - # . . call - e8/call kernel-string-equal?/disp32 - # . . discard args - 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP - # check-ints-equal(EAX, 0, msg) - # . . push args - 68/push "F - test-compare-kernel-string-with-longer-array"/imm32 - 68/push 0/imm32/false - 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 - c3/return - -# - helpers - -# print msg to stderr if a != b, otherwise print "." -check-ints-equal: # (a : int, b : int, msg : (address array byte)) -> boolean - # . prolog - 55/push-EBP - 89/copy 3/mod/direct 5/rm32/EBP . . . 4/r32/ESP . . # copy ESP to EBP - # . save registers - 51/push-ECX - 53/push-EBX - # load args into EAX, EBX and ECX - 8b/copy 1/mod/*+disp8 5/rm32/EBP . . . 0/r32/EAX 8/disp8 . # copy *(EBP+8) to EAX - 8b/copy 1/mod/*+disp8 5/rm32/EBP . . . 3/r32/EBX 0xc/disp8 . # copy *(EBP+12) to EBX - # if (EAX == b/EBX) print('.') and return - 39/compare 3/mod/direct 0/rm32/EAX . . . 3/r32/EBX . . # compare EAX and EBX - 75/jump-if-unequal $check-ints-equal:else/disp8 - # . write-stderr('.') - # . . push args - 68/push "."/imm32 - # . . call - e8/call write-stderr/disp32 - # . . discard args - 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP - # . return - eb/jump $check-ints-equal:end/disp8 - # otherwise print(msg) -$check-ints-equal:else: - # copy msg into ECX - 8b/copy 1/mod/*+disp8 5/rm32/EBP . . . 1/r32/ECX 0x10/disp8 . # copy *(EBP+16) to ECX - # print(ECX) - # . . push args - 51/push-ECX - # . . call - e8/call write-stderr/disp32 - # . . discard args - 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP - # print newline - # . . push args - 68/push Newline/imm32 - # . . call - e8/call write-stderr/disp32 - # . . discard args - 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP -$check-ints-equal:end: - # . restore registers - 5b/pop-to-EBX - 59/pop-to-ECX - # end - 89/copy 3/mod/direct 4/rm32/ESP . . . 5/r32/EBP . . # copy EBP to ESP - 5d/pop-to-EBP - 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 - # syscall(write, 2/stderr, (data) s+4, (size) *s) - # . . fd = 2 (stderr) - bb/copy-to-EBX 2/imm32 - # . . x = s+4 - 8b/copy 1/mod/*+disp8 5/rm32/EBP . . . 1/r32/ECX 8/disp8 . # copy *(EBP+8) to ECX - 81 0/subop/add 3/mod/direct 1/rm32/ECX . . . . . 4/imm32 # add to ECX - # . . size = *s - 8b/copy 1/mod/*+disp8 5/rm32/EBP . . . 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 - # . . syscall - b8/copy-to-EAX 4/imm32/write - cd/syscall 0x80/imm8 - # . restore registers - 5b/pop-to-EBX - 5a/pop-to-EDX - 59/pop-to-ECX - 58/pop-to-EAX - # . end - 89/copy 3/mod/direct 4/rm32/ESP . . . 5/r32/EBP . . # copy EBP to ESP - 5d/pop-to-EBP - c3/return - -== data 0x0a000000 - -Newline: - # size - 1/imm32 - # data - 0a/newline - -# for kernel-string-equal tests -Null-kernel-string: - 00/null - -_test-Abc-kernel-string: - 41/A 62/b 63/c 00/null - -# . . vim:nowrap:textwidth=0 |