diff options
Diffstat (limited to 'apps/factorial2.subx')
| -rw-r--r-- | apps/factorial2.subx | 59 |
1 files changed, 31 insertions, 28 deletions
diff --git a/apps/factorial2.subx b/apps/factorial2.subx index 7d303227..55723f75 100644 --- a/apps/factorial2.subx +++ b/apps/factorial2.subx @@ -20,31 +20,33 @@ == code -factorial: # n: int -> int/eax +factorial: # n: int -> _/eax: int # . prologue 55/push-ebp 89/<- %ebp 4/r32/esp - 53/push-ebx + # save registers + 51/push-ecx # if (n <= 1) return 1 b8/copy-to-eax 1/imm32 81 7/subop/compare *(ebp+8) 1/imm32 7e/jump-if-<= $factorial:end/disp8 - # var ebx: int = n-1 - 8b/-> *(ebp+8) 3/r32/ebx - 4b/decrement-ebx - # var eax: int = factorial(n-1) + # n > 1; return n * factorial(n-1) + 8b/-> *(ebp+8) 1/r32/ecx + 49/decrement-ecx + # var tmp/eax: int = factorial(n-1) # . . push args - 53/push-ebx + 51/push-ecx # . . call e8/call factorial/disp32 # . . discard args 81 0/subop/add %esp 4/imm32 - # return n * factorial(n-1) + # return n * tmp f7 4/subop/multiply-into-eax *(ebp+8) # TODO: check for overflow $factorial:end: + # restore registers + 59/pop-to-ecx # . epilogue - 5b/pop-to-ebx 89/<- %esp 5/r32/ebp 5d/pop-to-ebp c3/return @@ -73,7 +75,7 @@ Entry: # run tests if necessary, compute `factorial(5)` if not # . prologue 89/<- %ebp 4/r32/esp - # initialize heap + # initialize heap (needed by tests elsewhere) # . Heap = new-segment(Heap-size) # . . push args 68/push Heap/imm32 @@ -83,11 +85,21 @@ Entry: # run tests if necessary, compute `factorial(5)` if not # . . discard args 81 0/subop/add %esp 8/imm32 - # - if argc > 1 and argv[1] == "test", then return run_tests() - # if (argc <= 1) goto run-main + # if (argc <= 1) return factorial(5) 81 7/subop/compare *ebp 1/imm32 - 7e/jump-if-<= $run-main/disp8 - # if (!kernel-string-equal?(argv[1], "test")) goto run-main + 7f/jump-if-> $main:run-tests/disp8 + # . . push args + 68/push 5/imm32 + # . . call + e8/call factorial/disp32 + # . . discard args + 81 0/subop/add %esp 4/imm32 + # . + 89/<- %ebx 0/r32/eax + 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 @@ -96,24 +108,15 @@ Entry: # run tests if necessary, compute `factorial(5)` if not e8/call kernel-string-equal?/disp32 # . . discard args 81 0/subop/add %esp 8/imm32 - # . if (eax == false) goto run-main + # . if (eax == false) goto do-nothing 3d/compare-eax-and 0/imm32/false - 74/jump-if-= $run-main/disp8 + 74/jump-if-= $main:do-nothing/disp8 # run-tests() e8/call run-tests/disp32 - # syscall(exit, *Num-test-failures) + # exit(*Num-test-failures) 8b/-> *Num-test-failures 3/r32/ebx eb/jump $main:end/disp8 -$run-main: - # - otherwise return factorial(5) - # ebx = factorial(5) - # . . push args - 68/push 5/imm32 - # . . call - e8/call factorial/disp32 - # . . discard args - 81 0/subop/add %esp 4/imm32 - # - 89/<- %ebx 0/r32/eax +$main:do-nothing: + bb/copy-to-ebx 0/imm32 $main:end: e8/call syscall_exit/disp32 |