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| author | Kartik Agaram <vc@akkartik.com> | 2019-07-27 16:01:55 -0700 |
|---|---|---|
| committer | Kartik Agaram <vc@akkartik.com> | 2019-07-27 17:47:59 -0700 |
| commit | 6e1eeeebfb453fa7c871869c19375ce60fbd7413 (patch) | |
| tree | 539c4a3fdf1756ae79770d5c4aaf6366f1d1525e /subx/examples/ex10.subx | |
| parent | 8846a7f85cc04b77b2fe8a67b6d317723437b00c (diff) | |
| download | mu-6e1eeeebfb453fa7c871869c19375ce60fbd7413.tar.gz | |
5485 - promote SubX to top-level
Diffstat (limited to 'subx/examples/ex10.subx')
| -rw-r--r-- | subx/examples/ex10.subx | 72 |
1 files changed, 0 insertions, 72 deletions
diff --git a/subx/examples/ex10.subx b/subx/examples/ex10.subx deleted file mode 100644 index 51cc0a8c..00000000 --- a/subx/examples/ex10.subx +++ /dev/null @@ -1,72 +0,0 @@ -# String comparison: return 1 iff the two args passed in at the commandline are equal. -# -# To run (from the subx directory): -# $ ./subx translate examples/ex10.subx -o examples/ex10 -# $ ./subx run examples/ex10 abc abd -# Expected result: -# $ echo $? -# 0 # false - -== code 0x09000000 -# instruction effective address register displacement immediate -# . op subop mod rm32 base index scale r32 -# . 1-3 bytes 3 bits 2 bits 3 bits 3 bits 3 bits 2 bits 2 bits 0/1/2/4 bytes 0/1/2/4 bytes - -Entry: # return argv-equal(argv[1], argv[2]) -# At the start of a SubX program: -# argc: *ESP -# argv[0]: *(ESP+4) -# argv[1]: *(ESP+8) -# ... - # . prolog - 89/copy 3/mod/direct 5/rm32/EBP . . . 4/r32/ESP . . # copy ESP to EBP - # argv-equal(argv[1], argv[2]) - # . . push argv[2] - ff 6/subop/push 1/mod/*+disp8 5/rm32/EBP . . . . 0xc/disp8 . # push *(EBP+12) - # . . push argv[1] - ff 6/subop/push 1/mod/*+disp8 5/rm32/EBP . . . . 8/disp8 . # push *(EBP+8) - # . . call - e8/call argv-equal/disp32 - # syscall(exit, EAX) - 89/copy 3/mod/direct 3/rm32/EBX . . . 0/r32/EAX . . # copy EAX to EBX - b8/copy-to-EAX 1/imm32/exit - cd/syscall 0x80/imm8 - -# compare two null-terminated ascii strings -# reason for the name: the only place we should have null-terminated ascii strings is from commandline args -argv-equal: # (s1, s2) : null-terminated ascii strings -> EAX : boolean - # initialize s1 (ECX) and s2 (EDX) - 8b/copy 1/mod/*+disp8 4/rm32/sib 4/base/ESP 4/index/none . 1/r32/ECX 4/disp8 . # copy *(ESP+4) to ECX - 8b/copy 1/mod/*+disp8 4/rm32/sib 4/base/ESP 4/index/none . 2/r32/EDX 8/disp8 . # copy *(ESP+8) to EDX -$argv-equal:loop: - # c1/EAX, c2/EBX = *s1, *s2 - b8/copy-to-EAX 0/imm32 - 8a/copy-byte 0/mod/indirect 1/rm32/ECX . . . 0/r32/AL . . # copy byte at *ECX to AL - bb/copy-to-EBX 0/imm32 - 8a/copy-byte 0/mod/indirect 2/rm32/EDX . . . 3/r32/BL . . # copy byte at *EDX to BL - # if (c1 == 0) break - 3d/compare-EAX-and 0/imm32 - 74/jump-if-equal $argv-equal:break/disp8 - # if (c1 != c2) return false - 39/compare 3/mod/direct 0/rm32/EAX . . . 3/r32/EBX . . # compare EAX and EBX - 75/jump-if-not-equal $argv-equal:false/disp8 - # ++s1, ++s2 - 41/increment-ECX - 42/increment-EDX - # end while - eb/jump $argv-equal:loop/disp8 -$argv-equal:break: - # if (c2 == 0) return true - 81 7/subop/compare 3/mod/direct 3/rm32/EBX . . . . . 0/imm32 # compare EBX - 75/jump-if-not-equal $argv-equal:false/disp8 -$argv-equal:success: - b8/copy-to-EAX 1/imm32 - c3/return - # return false -$argv-equal:false: - b8/copy-to-EAX 0/imm32 - c3/return - -== data 0x0a000000 - -# . . vim:nowrap:textwidth=0 |