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| author | Kartik Agaram <vc@akkartik.com> | 2018-08-03 23:23:39 -0700 |
|---|---|---|
| committer | Kartik Agaram <vc@akkartik.com> | 2018-08-03 23:23:39 -0700 |
| commit | 12adb3da8a8979c207b2e7fd17bdb05bacefeb44 (patch) | |
| tree | 12c1a96ffe7feb8b41613e0b2cead1c3919db8d9 /subx/ex7.subx | |
| parent | 85173b622021de062706df81947df7ae2300b654 (diff) | |
| download | mu-12adb3da8a8979c207b2e7fd17bdb05bacefeb44.tar.gz | |
4467
Diffstat (limited to 'subx/ex7.subx')
| -rw-r--r-- | subx/ex7.subx | 56 |
1 files changed, 28 insertions, 28 deletions
diff --git a/subx/ex7.subx b/subx/ex7.subx index fab91b6a..4474e110 100644 --- a/subx/ex7.subx +++ b/subx/ex7.subx @@ -8,80 +8,80 @@ # 120 == 0x08048054 # code segment, after leaving room for ELF header -# 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 +# 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: # prepare to make a call # 54 - 55/push # push EBP + 55/push # push EBP # 55 - 89/copy 3/mod/direct 5/rm32/EBP 4/r32/ESP # copy ESP to EBP + 89/copy 3/mod/direct 5/rm32/EBP 4/r32/ESP # copy ESP to EBP # 57 # factorial(5) - 68/push 5/imm32 # push 5 + 68/push 5/imm32 # push 5 # 5c - e8/call factorial/disp32 + e8/call factorial/disp32 # 61 # discard arg - 5a/pop # pop into EDX + 5a/pop # pop into EDX # 62 # clean up after call - 89/copy 3/mod/direct 4/rm32/ESP 5/r32/EBP # copy EBP to ESP + 89/copy 3/mod/direct 4/rm32/ESP 5/r32/EBP # copy EBP to ESP # 64 - 5d/pop # pop to EBP + 5d/pop # pop to EBP # exit(EAX) # 65 - 89/copy 3/mod/direct 3/rm32/EBX 0/r32/EAX # copy EAX to EBX + 89/copy 3/mod/direct 3/rm32/EBX 0/r32/EAX # copy EAX to EBX # 67 - b8/copy 1/imm32 # copy 1 to EAX + b8/copy 1/imm32 # copy 1 to EAX # 6c - cd/syscall 0x80/imm8 # int 80h + cd/syscall 0x80/imm8 # int 80h # factorial(n) # 6e factorial: # initialize n - 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 1/mod/*+disp8 4/rm32/sib 4/base/ESP 4/index/none 2/r32/EDX 4/disp8 # copy *(ESP+4) to EDX # 72 # initialize EAX to 1 (base case) - b8/copy 1/imm32 # copy 1 to EAX + b8/copy 1/imm32 # copy 1 to EAX # 77 # if (n <= 1) jump exit - 81 7/subop/compare 3/mod/direct 2/rm32/EDX 1/imm32 # compare EDX with 1 + 81 7/subop/compare 3/mod/direct 2/rm32/EDX 1/imm32 # compare EDX with 1 # 7d - 7e/jump-if factorial:exit/disp8 # jump if <= to exit + 7e/jump-if factorial:exit/disp8 # jump if <= to exit # 7f # EBX: n-1 - 89/copy 3/mod/direct 3/rm32/EBX 2/r32/EDX # copy EDX to EBX + 89/copy 3/mod/direct 3/rm32/EBX 2/r32/EDX # copy EDX to EBX # 81 - 81 5/subop/subtract 3/mod/direct 3/rm32/EBX 1/imm32 # subtract 1 from EBX + 81 5/subop/subtract 3/mod/direct 3/rm32/EBX 1/imm32 # subtract 1 from EBX # 87 # prepare call - 55/push # push EBP + 55/push # push EBP # 88 - 89/copy 3/mod/direct 5/rm32/EBP 4/r32/ESP # copy ESP to EBP + 89/copy 3/mod/direct 5/rm32/EBP 4/r32/ESP # copy ESP to EBP # EAX: factorial(n-1) # 8a - 53/push # push EBX + 53/push # push EBX # 8b - e8/call factorial/disp32 + e8/call factorial/disp32 # 90 # discard arg - 5e/pop # pop into ESI + 5e/pop # pop into ESI # 91 # clean up after call - 89/copy 3/mod/direct 4/rm32/ESP 5/r32/EBP # copy EBP to ESP + 89/copy 3/mod/direct 4/rm32/ESP 5/r32/EBP # copy EBP to ESP # 93 - 5d/pop # pop to EBP + 5d/pop # pop to EBP # 94 # refresh n - 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 1/mod/*+disp8 4/rm32/sib 4/base/ESP 4/index/none 2/r32/EDX 4/disp8 # copy *(ESP+4) to EDX # 98 # return n * factorial(n-1) - 0f af/multiply 3/mod/direct 2/rm32/EDX 0/r32/EAX # multiply EDX (n) into EAX (factorial(n-1)) + 0f af/multiply 3/mod/direct 2/rm32/EDX 0/r32/EAX # multiply EDX (n) into EAX (factorial(n-1)) # TODO: check for overflow # 9b factorial:exit: |