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| author | Kartik Agaram <vc@akkartik.com> | 2018-07-26 12:19:02 -0700 |
|---|---|---|
| committer | Kartik Agaram <vc@akkartik.com> | 2018-07-26 12:19:02 -0700 |
| commit | 6e51c60c699f795f14e49744a10f91d9609b044e (patch) | |
| tree | 56b7b3372929abb8850a99141341395d50518c47 /subx/ex5.subx | |
| parent | 7da8da495fbe9422f13198a83193d4b5477bf8f6 (diff) | |
| download | mu-6e51c60c699f795f14e49744a10f91d9609b044e.tar.gz | |
4424
Clean up format of example programs.
Diffstat (limited to 'subx/ex5.subx')
| -rw-r--r-- | subx/ex5.subx | 37 |
1 files changed, 18 insertions, 19 deletions
diff --git a/subx/ex5.subx b/subx/ex5.subx index b74af463..65ca4807 100644 --- a/subx/ex5.subx +++ b/subx/ex5.subx @@ -5,44 +5,43 @@ # $ subx run ex5 == 0x08048054 # code segment, after leaving room for ELF header and segment headers -# instruction effective address operand displacement immediate -# op subop mod rm32 base index scale r32 -# 1-3 bytes 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 ## function main # prolog - 55 # push EBP - 89 3/mod/direct 5/rm32/EBP 4/r32/ESP # copy ESP to EBP + 55 # push EBP + 89 3/mod/direct 5/rm32/EBP 4/r32/ESP # copy ESP to EBP # allocate x on the stack - 81 5/subop/subtract 3/mod/direct 4/rm32/ESP 4/imm32 # subtract 4 bytes from ESP + 81 5/subop/subtract 3/mod/direct 4/rm32/ESP 4/imm32 # subtract 4 bytes from ESP ## read(stdin, x, 1) # fd = 0 (stdin) - bb 0/imm32 # copy 0 to EBX + bb 0/imm32 # copy 0 to EBX # set location to read character to - 89 3/mod/direct 1/rm32/ECX 5/r32/EBP # copy EBP to ECX + 89 3/mod/direct 1/rm32/ECX 5/r32/EBP # copy EBP to ECX # size = 1 character - ba 1/imm32 # copy 1 to EDX + ba 1/imm32 # copy 1 to EDX # syscall = read - b8 3/imm32 # copy 3 to EAX + b8 3/imm32 # copy 3 to EAX # call - cd 0x80/imm8 # int 80h + cd 0x80/imm8 # int 80h ## write(stdout, x, 1) # fd = 1 (stdout) - bb 1/imm32 # copy 1 to EBX + bb 1/imm32 # copy 1 to EBX # set location of character to write out - 89 3/mod/direct 1/rm32/ECX 5/r32/EBP # copy EBP to ECX - # ModR/M: 11 (direct mode) 101 (src EBP) 001 (dest ECX) + 89 3/mod/direct 1/rm32/ECX 5/r32/EBP # copy EBP to ECX # size = 1 character - ba 1/imm32 # copy 1 to EDX + ba 1/imm32 # copy 1 to EDX # syscall = write - b8 4/imm32 # copy 4 to EAX + b8 4/imm32 # copy 4 to EAX # call - cd 0x80/imm8 # int 80h + cd 0x80/imm8 # int 80h ## exit(EBX) - b8 1/imm32 # copy 1 to EAX - cd 0x80/imm8 # int 80h + b8 1/imm32 # copy 1 to EAX + cd 0x80/imm8 # int 80h # vim:ft=subx:nowrap |