40 lines
788 B
Plaintext
40 lines
788 B
Plaintext
# Read a character from stdin, save it to a global, write it to stdout.
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#
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# To run:
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# $ bootstrap/bootstrap translate ex4.subx -o ex4
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# $ bootstrap/bootstrap run ex4
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== data
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# the global variable we save to
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X:
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0/imm32 # space for read() to write to
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== code
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Entry:
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# read(stdin, X, 1)
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# . fd = 0 (stdin)
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bb/copy-to-ebx 0/imm32
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# . data = X (location to write result to)
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b9/copy-to-ecx X/imm32
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# . size = 1 character
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ba/copy-to-edx 1/imm32
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# . syscall
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e8/call syscall_read/disp32
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# write(stdout, X, 1)
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# . fd = 1 (stdout)
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bb/copy-to-ebx 1/imm32
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# . initialize X (location to read from)
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b9/copy-to-ecx X/imm32
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# . size = 1 character
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ba/copy-to-edx 1/imm32
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# . syscall
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e8/call syscall_write/disp32
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# exit(ebx)
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e8/call syscall_exit/disp32
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# . . vim:nowrap:textwidth=0
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