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| author | Kartik K. Agaram <vc@akkartik.com> | 2021-07-16 08:09:42 -0700 |
|---|---|---|
| committer | Kartik K. Agaram <vc@akkartik.com> | 2021-07-16 08:28:56 -0700 |
| commit | 44d26b77c45668c9b0c99894a4294cec004361fe (patch) | |
| tree | 68a5dcd4971873efd4ce184e9bf9a531c2161813 /linux/ex9.subx | |
| parent | ac45f097153afd3a89f43886e4124c5b2c26b98a (diff) | |
| download | mu-44d26b77c45668c9b0c99894a4294cec004361fe.tar.gz | |
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Diffstat (limited to 'linux/ex9.subx')
| -rw-r--r-- | linux/ex9.subx | 52 |
1 files changed, 0 insertions, 52 deletions
diff --git a/linux/ex9.subx b/linux/ex9.subx deleted file mode 100644 index cbab3aa9..00000000 --- a/linux/ex9.subx +++ /dev/null @@ -1,52 +0,0 @@ -# Example showing arg order on the stack. -# -# Show difference between ascii codes of first letter of first arg and first -# letter of second arg. -# -# To run: -# $ bootstrap/bootstrap translate ex9.subx -o ex9 -# $ bootstrap/bootstrap run ex9 z x -# Expected result: -# $ echo $? -# 2 -# -# At the start of a SubX program: -# argc: *esp -# argv[0]: *(esp+4) -# argv[1]: *(esp+8) -# ... -# Locals start from esp-4 downwards. - -== code -# instruction effective address register 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 - -Entry: - # . prologue - 89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp - # ascii-difference(argv[1], argv[2]) - # . . push argv[2] - ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 0xc/disp8 . # push *(ebp+12) - # . . push argv[1] - ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 8/disp8 . # push *(ebp+8) - # . . call - e8/call ascii-difference/disp32 - # . . discard args - 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp - # exit(eax) - 89/copy 3/mod/direct 3/rm32/ebx . . . 0/r32/eax . . # copy eax to ebx - e8/call syscall_exit/disp32 - -ascii-difference: # (s1, s2): null-terminated ascii strings - # a = first letter of s1 (ecx) - 8b/copy 1/mod/*+disp8 4/rm32/sib 4/base/esp 4/index/none . 0/r32/eax 4/disp8 . # copy *(esp+4) to eax - 8b/copy 0/mod/indirect 0/rm32/eax . . . 0/r32/eax . . # copy *eax to eax - # b = first letter of s2 (edx) - 8b/copy 1/mod/*+disp8 4/rm32/sib 4/base/esp 4/index/none . 1/r32/ecx 8/disp8 # copy *(esp+8) to ecx - 8b/copy 0/mod/indirect 1/rm32/ecx . . . 1/r32/ecx . . # copy *ecx to ecx - # a-b - 29/subtract 3/mod/direct 0/rm32/eax . . . 1/r32/ecx . . # subtract ecx from eax - c3/return - -# . . vim:nowrap:textwidth=0 |