diff options
Diffstat (limited to 'subx/examples')
| -rwxr-xr-x | subx/examples/ex11 | bin | 1062 -> 1125 bytes | |||
| -rw-r--r-- | subx/examples/ex11.subx | 105 |
2 files changed, 53 insertions, 52 deletions
diff --git a/subx/examples/ex11 b/subx/examples/ex11 index d68fd5ad..78b7a6ae 100755 --- a/subx/examples/ex11 +++ b/subx/examples/ex11 Binary files differdiff --git a/subx/examples/ex11.subx b/subx/examples/ex11.subx index 3f0805af..cae4de40 100644 --- a/subx/examples/ex11.subx +++ b/subx/examples/ex11.subx @@ -1,9 +1,9 @@ ## Null-terminated vs length-prefixed ascii strings. # # By default we create strings with a 4-byte length prefix rather than a null suffix. -# However, commandline arguments come null-prefixed from the Linux kernel. -# This example shows a helper that can compare a commandline argument with the -# (length-prefixed) literal string "target". +# 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 @@ -15,6 +15,7 @@ # would cause tests to not run, rather than to fail as we'd like.) == 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 @@ -28,7 +29,7 @@ # 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 +kernel_string_equal: # s : null-terminated ascii string, benchmark : length-prefixed ascii string -> EAX : boolean # prolog 55/push-EBP 89/copy 3/mod/direct 5/rm32/EBP . . . 4/r32/ESP . . # copy ESP to EBP @@ -63,9 +64,9 @@ argv_equal: # s : null-terminated ascii string, benchmark : length-prefixed asc # initialize loop counter i into ECX b9/copy . . . . . . . 0/imm32/exit # copy 1 to ECX # while (i/ECX < n/EDX) -$argv_loop: +$kernel_string_loop: 39/compare 3/mod/direct 1/rm32/ECX . . . 2/r32/EDX . . # compare ECX with EDX - 74/jump-if-equal $argv_break/disp8 + 74/jump-if-equal $kernel_string_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 @@ -73,29 +74,29 @@ $argv_loop: 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 + 74/jump-if-equal $kernel_string_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 + 75/jump-if-not-equal $kernel_string_fail/disp8 # ++s1, ++s2, ++i 41/inc-ECX 46/inc-ESI 47/inc-EDI # end while - eb/jump $argv_loop/disp8 -$argv_break: + eb/jump $kernel_string_loop/disp8 +$kernel_string_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 + 75/jump-if-not-equal $kernel_string_fail/disp8 b8/copy . . . . . . . 1/imm32 # copy 1 to EAX - eb/jump $argv_end/disp8 + eb/jump $kernel_string_end/disp8 # return false -$argv_fail: +$kernel_string_fail: b8/copy . . . . . . . 0/imm32 # copy 0 to EAX -$argv_end: +$kernel_string_end: # restore registers 5f/pop-to-EDI 5e/pop-to-ESI @@ -109,18 +110,18 @@ $argv_end: ## tests -test_compare_null_argv_with_empty_array: - # EAX = argv_equal(Null_argv, "") +test_compare_null_kernel_string_with_empty_array: + # EAX = kernel_string_equal(Null_kernel_string, "") # push args 68/push ""/imm32 - 68/push Null_argv/imm32 + 68/push Null_kernel_string/imm32 # call - e8/call argv_equal/disp32 + e8/call kernel_string_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, msg) # push args - 68/push "F - test_compare_null_argv_with_empty_array"/imm32 + 68/push "F - test_compare_null_kernel_string_with_empty_array"/imm32 68/push 1/imm32/true 50/push-EAX # call @@ -129,18 +130,18 @@ test_compare_null_argv_with_empty_array: 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") +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_argv/imm32 + 68/push Null_kernel_string/imm32 # call - e8/call argv_equal/disp32 + e8/call kernel_string_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, msg) # push args - 68/push "F - test_compare_null_argv_with_non_empty_array"/imm32 + 68/push "F - test_compare_null_kernel_string_with_non_empty_array"/imm32 68/push 0/imm32/false 50/push-EAX # call @@ -149,18 +150,18 @@ test_compare_null_argv_with_non_empty_array: 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") +test_compare_kernel_string_with_equal_array: + # EAX = kernel_string_equal(Abc_kernel_string, "Abc") # push args 68/push "Abc"/imm32 - 68/push Abc_argv/imm32 + 68/push Abc_kernel_string/imm32 # call - e8/call argv_equal/disp32 + e8/call kernel_string_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, msg) # push args - 68/push "F - test_compare_argv_with_equal_array"/imm32 + 68/push "F - test_compare_kernel_string_with_equal_array"/imm32 68/push 1/imm32/true 50/push-EAX # call @@ -169,18 +170,18 @@ test_compare_argv_with_equal_array: 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") +test_compare_kernel_string_with_inequal_array: + # EAX = kernel_string_equal(Abc_kernel_string, "Adc") # push args 68/push "Adc"/imm32 - 68/push Abc_argv/imm32 + 68/push Abc_kernel_string/imm32 # call - e8/call argv_equal/disp32 + e8/call kernel_string_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, msg) # push args - 68/push "F - test_compare_argv_with_equal_array"/imm32 + 68/push "F - test_compare_kernel_string_with_equal_array"/imm32 68/push 0/imm32/false 50/push-EAX # call @@ -189,18 +190,18 @@ test_compare_argv_with_inequal_array: 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, "") +test_compare_kernel_string_with_empty_array: + # EAX = kernel_string_equal(Abc_kernel_string, "") # push args 68/push ""/imm32 - 68/push Abc_argv/imm32 + 68/push Abc_kernel_string/imm32 # call - e8/call argv_equal/disp32 + e8/call kernel_string_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) # push args - 68/push "F - test_compare_argv_with_equal_array"/imm32 + 68/push "F - test_compare_kernel_string_with_equal_array"/imm32 68/push 0/imm32/false 50/push-EAX # call @@ -209,18 +210,18 @@ test_compare_argv_with_empty_array: 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") +test_compare_kernel_string_with_shorter_array: + # EAX = kernel_string_equal(Abc_kernel_string, "Ab") # push args 68/push "Ab"/imm32 - 68/push Abc_argv/imm32 + 68/push Abc_kernel_string/imm32 # call - e8/call argv_equal/disp32 + e8/call kernel_string_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) # push args - 68/push "F - test_compare_argv_with_shorter_array"/imm32 + 68/push "F - test_compare_kernel_string_with_shorter_array"/imm32 68/push 0/imm32/false 50/push-EAX # call @@ -229,18 +230,18 @@ test_compare_argv_with_shorter_array: 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") +test_compare_kernel_string_with_longer_array: + # EAX = kernel_string_equal(Abc_kernel_string, "Abcd") # push args 68/push "Abcd"/imm32 - 68/push Abc_argv/imm32 + 68/push Abc_kernel_string/imm32 # call - e8/call argv_equal/disp32 + e8/call kernel_string_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) # push args - 68/push "F - test_compare_argv_with_longer_array"/imm32 + 68/push "F - test_compare_kernel_string_with_longer_array"/imm32 68/push 0/imm32/false 50/push-EAX # call @@ -339,10 +340,10 @@ Newline: # data 0a/newline -# for argv_equal tests -Null_argv: +# for kernel_string_equal tests +Null_kernel_string: 00/null -Abc_argv: +Abc_kernel_string: 41/A 62/b 63/c 00/null # vim:ft=subx:nowrap:so=0 |