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Diffstat (limited to 'examples/ex5.subx')
| -rw-r--r-- | examples/ex5.subx | 45 |
1 files changed, 45 insertions, 0 deletions
diff --git a/examples/ex5.subx b/examples/ex5.subx new file mode 100644 index 00000000..6f5b1d90 --- /dev/null +++ b/examples/ex5.subx @@ -0,0 +1,45 @@ +# Read a character from stdin, save it to a local on the stack, write it to stdout. +# +# To run (from the subx directory): +# $ ./subx translate examples/ex5.subx -o examples/ex5 +# $ ./subx run examples/ex5 + +== 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: + + # allocate x on the stack + 81 5/subop/subtract 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # subtract from ESP + + # syscall(read, stdin, x, 1) + # . fd = 0 (stdin) + bb/copy-to-EBX 0/imm32 + # . data = x (location to write result to) + 8d/copy-address 1/mod/*+disp8 4/rm32/sib 4/base/ESP 4/index/none 1/r32/ECX 4/disp8 . # copy ESP+4 to ECX + # . size = 1 character + ba/copy-to-EDX 1/imm32 + # . syscall + b8/copy-to-EAX 3/imm32/read + cd/syscall 0x80/imm8 + + # syscall(write, stdout, x, 1) + # . fd = 1 (stdout) + bb/copy-to-EBX 1/imm32 + # . data = x (location to read from) + 8d/copy-address 1/mod/*+disp8 4/rm32/sib 4/base/ESP 4/index/none 1/r32/ECX 4/disp8 . # copy ESP+4 to ECX + # . size = 1 character + ba/copy-to-EDX 1/imm32 + # . syscall + b8/copy-to-EAX 4/imm32/write + cd/syscall 0x80/imm8 + + # syscall(exit, EBX) + b8/copy-to-EAX 1/imm32/exit + cd/syscall 0x80/imm8 + +== data 0x0a000000 + +# . . vim:nowrap:textwidth=0 |