diff options
Diffstat (limited to 'apps/factorial.subx')
| -rw-r--r-- | apps/factorial.subx | 64 |
1 files changed, 34 insertions, 30 deletions
diff --git a/apps/factorial.subx b/apps/factorial.subx index b027696e..586592f5 100644 --- a/apps/factorial.subx +++ b/apps/factorial.subx @@ -18,21 +18,21 @@ # . 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 -factorial: # n: int -> int/eax +factorial: # n: int -> _/eax: int # . prologue 55/push-ebp 89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp - 53/push-ebx + 51/push-ecx # if (n <= 1) return 1 b8/copy-to-eax 1/imm32 81 7/subop/compare 1/mod/*+disp8 5/rm32/ebp . . . . 8/disp8 1/imm32 # compare *(ebp+8) 7e/jump-if-<= $factorial:end/disp8 - # var ebx: int = n-1 - 8b/copy 1/mod/*+disp8 5/rm32/ebp . . 3/r32/ebx 8/disp8 . # copy *(ebp+8) to ebx - 4b/decrement-ebx + # var ecx: int = n-1 + 8b/copy 1/mod/*+disp8 5/rm32/ebp . . 1/r32/ecx 8/disp8 . # copy *(ebp+8) to ecx + 49/decrement-ecx # var eax: int = factorial(n-1) # . . push args - 53/push-ebx + 51/push-ecx # . . call e8/call factorial/disp32 # . . discard args @@ -41,8 +41,9 @@ factorial: # n: int -> int/eax f7 4/subop/multiply 1/mod/*+disp8 5/rm32/ebp . . 8/disp8 . # multiply *(ebp+8) into eax # TODO: check for overflow $factorial:end: + # restore registers + 59/pop-to-ecx # . epilogue - 5b/pop-to-ebx 89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp 5d/pop-to-ebp c3/return @@ -71,7 +72,7 @@ Entry: # run tests if necessary, compute `factorial(5)` if not # . prologue 89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp - # initialize heap + # initialize heap (needed by tests elsewhere) # . Heap = new-segment(Heap-size) # . . push args 68/push Heap/imm32 @@ -81,29 +82,10 @@ Entry: # run tests if necessary, compute `factorial(5)` if not # . . discard args 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp - # - if argc > 1 and argv[1] == "test", then return run_tests() - # if (argc <= 1) goto run-main - 81 7/subop/compare 1/mod/*+disp8 5/rm32/ebp . . . . 0/disp8 1/imm32 # compare *ebp - 7e/jump-if-<= $run-main/disp8 - # if (!kernel-string-equal?(argv[1], "test")) goto run-main - # . eax = kernel-string-equal?(argv[1], "test") - # . . push args - 68/push "test"/imm32 - ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 8/disp8 . # push *(ebp+8) - # . . call - e8/call kernel-string-equal?/disp32 - # . . discard args - 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp - # . if (eax == false) goto run-main - 3d/compare-eax-and 0/imm32/false - 74/jump-if-= $run-main/disp8 - # run-tests() - e8/call run-tests/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 - eb/jump $main:end/disp8 + # if (argc <= 1) return factorial(5) $run-main: - # - otherwise print factorial(5) + 81 7/subop/compare 1/mod/*+disp8 5/rm32/ebp . . . . 0/disp8 1/imm32 # compare *ebp + 7f/jump-if-> $main:run-tests/disp8 # eax = factorial(5) # . . push args 68/push 5/imm32 @@ -143,6 +125,28 @@ $run-main: 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp # 89/copy 3/mod/direct 3/rm32/ebx . . . 0/r32/eax . . # copy eax to ebx + eb/jump $main:end/disp8 +$main:run-tests: + # otherwise if first arg is "test", then return run_tests() + # if (!kernel-string-equal?(argv[1], "test")) goto do-nothing + # . eax = kernel-string-equal?(argv[1], "test") + # . . push args + 68/push "test"/imm32 + ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 8/disp8 . # push *(ebp+8) + # . . call + e8/call kernel-string-equal?/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp + # . if (eax == false) goto do-nothing + 3d/compare-eax-and 0/imm32/false + 74/jump-if-= $main:do-nothing/disp8 + # run-tests() + e8/call run-tests/disp32 + # 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 + eb/jump $main:end/disp8 +$main:do-nothing: + bb/copy-to-ebx 0/imm32 $main:end: e8/call syscall_exit/disp32 |