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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 /examples/ex7.subx | |
| parent | 8846a7f85cc04b77b2fe8a67b6d317723437b00c (diff) | |
| download | mu-6e1eeeebfb453fa7c871869c19375ce60fbd7413.tar.gz | |
5485 - promote SubX to top-level
Diffstat (limited to 'examples/ex7.subx')
| -rw-r--r-- | examples/ex7.subx | 107 |
1 files changed, 107 insertions, 0 deletions
diff --git a/examples/ex7.subx b/examples/ex7.subx new file mode 100644 index 00000000..d3b33f23 --- /dev/null +++ b/examples/ex7.subx @@ -0,0 +1,107 @@ +# Example showing file syscalls. +# +# Create a file, open it for writing, write a character to it, close it, open +# it for reading, read a character from it, close it, delete it, and return +# the character read. +# +# To run (from the subx directory): +# $ ./subx translate examples/ex7.subx -o examples/ex7 +# $ ./subx run examples/ex7 +# Expected result: +# $ echo $? +# 97 + +== 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: + # syscall(creat, Filename) + bb/copy-to-EBX Filename/imm32 + b9/copy-to-ECX 0x180/imm32/fixed-perms + b8/copy-to-EAX 8/imm32/creat + cd/syscall 0x80/imm8 + + # stream = syscall(open, Filename, O_WRONLY, 0) # we can't use 'fd' because it looks like a hex byte + bb/copy-to-EBX Filename/imm32 + b9/copy-to-ECX 1/imm32/wronly + ba/copy-to-EDX 0x180/imm32/fixed-perms + b8/copy-to-EAX 5/imm32/open + cd/syscall 0x80/imm8 + # save stream + bb/copy-to-EBX Stream/imm32 + 89/copy 0/mod/indirect 3/rm32/EBX . . . 0/r32/EAX . . # copy EAX to *EBX + + # syscall(write, Stream, "a", 1) + # . load stream + bb/copy-to-EBX Stream/imm32 + 8b/copy 0/mod/indirect 3/rm32/EBX . . . 3/r32/EBX . . # copy *EBX to EBX + # . + b9/copy-to-ECX A/imm32 + ba/copy-to-EDX 1/imm32/size + b8/copy-to-EAX 4/imm32/write + cd/syscall 0x80/imm8 + + # syscall(close, Stream) + # . load stream + bb/copy-to-EBX Stream/imm32 + 8b/copy 0/mod/indirect 3/rm32/EBX . . . 3/r32/EBX . . # copy *EBX to EBX + # . + b8/copy-to-EAX 6/imm32/close + cd/syscall 0x80/imm8 + + # stream = syscall(open, Filename, O_RDONLY, 0) + bb/copy-to-EBX Filename/imm32 + b9/copy-to-ECX 0/imm32/rdonly + ba/copy-to-EDX 0x180/imm32/fixed-perms + b8/copy-to-EAX 5/imm32/open + cd/syscall 0x80/imm8 + # . save Stream + bb/copy-to-EBX Stream/imm32 + 89/copy 0/mod/indirect 3/rm32/EBX . . . 0/r32/EAX . . # copy EAX to *EBX + + # syscall(read, Stream, B, 1) + # . load stream + bb/copy-to-EBX Stream/imm32 + 8b/copy 0/mod/indirect 3/rm32/EBX . . . 3/r32/EBX . . # copy *EBX to EBX + # . + b9/copy-to-ECX B/imm32 + ba/copy-to-EDX 1/imm32/size + b8/copy-to-EAX 3/imm32/read + cd/syscall 0x80/imm8 + + # syscall(close, Stream) + # . load stream + bb/copy-to-EBX Stream/imm32 + 8b/copy 0/mod/indirect 3/rm32/EBX . . . 3/r32/EBX . . # copy *EBX to EBX + # + b8/copy-to-EAX 6/imm32/close + cd/syscall 0x80/imm8 + + # syscall(unlink, filename) + bb/copy-to-EBX Filename/imm32 + b8/copy-to-EAX 0xa/imm32/unlink + cd/syscall 0x80/imm8 + + # syscall(exit, b) + # . load b + bb/copy-to-EBX B/imm32 + 8b/copy 0/mod/indirect 3/rm32/EBX . . . 3/r32/EBX . . # copy *EBX to EBX + # + b8/copy-to-EAX 1/imm32/exit + cd/syscall 0x80/imm8 + +== data 0x0a000000 + +Stream: + 0/imm32 +A: + 61/imm32/A +B: + 0/imm32 +Filename: + 2e 66 6f 6f 00 00 00 00 +# . f o o null + +# . . vim:nowrap:textwidth=0 |