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mu/subx/examples/ex7.subx

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4530 - create an apps/ directory
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## 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.
4456 - example with function calls: factorial I found a bug with multiply in the process; another case (after the swap of call/jump opcodes in 4453) where there's no point improving testing. Unit tests can only tell us if our instructions are internally consistent. Validating against a real machine has to be manual. I'm definitely feeling the pain of debugging machine code now, that's for sure. Going over an instruction trace, comparing the state of registers line by line.
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#
# To run:
4624 Start requiring a '-o' flag to designate the output binary when translating. Things currently get funky if you pass in multiple inputs, but that's ok. This is the first step to supporting multiple input files for a single output binary.
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# $ subx translate ex8.subx -o ex8
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# $ subx run ex8
4456 - example with function calls: factorial I found a bug with multiply in the process; another case (after the swap of call/jump opcodes in 4453) where there's no point improving testing. Unit tests can only tell us if our instructions are internally consistent. Validating against a real machine has to be manual. I'm definitely feeling the pain of debugging machine code now, that's for sure. Going over an instruction trace, comparing the state of registers line by line.
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# Expected result:
# $ echo $?
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# 97
4456 - example with function calls: factorial I found a bug with multiply in the process; another case (after the swap of call/jump opcodes in 4453) where there's no point improving testing. Unit tests can only tell us if our instructions are internally consistent. Validating against a real machine has to be manual. I'm definitely feeling the pain of debugging machine code now, that's for sure. Going over an instruction trace, comparing the state of registers line by line.
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== code
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# instruction effective address operand 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
4456 - example with function calls: factorial I found a bug with multiply in the process; another case (after the swap of call/jump opcodes in 4453) where there's no point improving testing. Unit tests can only tell us if our instructions are internally consistent. Validating against a real machine has to be manual. I'm definitely feeling the pain of debugging machine code now, that's for sure. Going over an instruction trace, comparing the state of registers line by line.
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4561
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# creat(filename)
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bb/copy . . . . . . . filename/imm32 # copy to EBX
b9/copy . . . . . . . 0x180/imm32/fixed-perms # copy to ECX
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b8/copy . . . . . . . 8/imm32/creat # copy 8 to EAX
4581 Even more cuddling. We want to keep lines short where the opcode and operands are self-explanatory. If there are any implicit registers, etc., we'll continue to do the table layout. The first two columns look messy now; let's see how this goes. Maybe I'll give up on the tabular layout altogether, just string args with a single space.
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cd/syscall 0x80/imm8
4456 - example with function calls: factorial I found a bug with multiply in the process; another case (after the swap of call/jump opcodes in 4453) where there's no point improving testing. Unit tests can only tell us if our instructions are internally consistent. Validating against a real machine has to be manual. I'm definitely feeling the pain of debugging machine code now, that's for sure. Going over an instruction trace, comparing the state of registers line by line.
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4561
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# stream = open(filename, O_WRONLY, 0) # we can't use 'fd' because it looks like a hex byte
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bb/copy . . . . . . . filename/imm32 # copy to EBX
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b9/copy . . . . . . . 1/imm32/wronly # copy 1 to ECX
ba/copy . . . . . . . 0x180/imm32/fixed-perms # copy 0 to EDX
b8/copy . . . . . . . 5/imm32/open # copy 5 to EAX
4581 Even more cuddling. We want to keep lines short where the opcode and operands are self-explanatory. If there are any implicit registers, etc., we'll continue to do the table layout. The first two columns look messy now; let's see how this goes. Maybe I'll give up on the tabular layout altogether, just string args with a single space.
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cd/syscall 0x80/imm8
4561
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# save stream
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bb/copy . . . . . . . stream/imm32 # copy to EBX
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89/copy 0/mod/indirect 3/rm32/EBX 0/r32/EAX # copy EAX to *EBX
4456 - example with function calls: factorial I found a bug with multiply in the process; another case (after the swap of call/jump opcodes in 4453) where there's no point improving testing. Unit tests can only tell us if our instructions are internally consistent. Validating against a real machine has to be manual. I'm definitely feeling the pain of debugging machine code now, that's for sure. Going over an instruction trace, comparing the state of registers line by line.
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4561
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# write(stream, "a", 1)
# load stream
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bb/copy . . . . . . . stream/imm32 # copy to EBX
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8b/copy 0/mod/indirect 3/rm32/EBX 3/r32/EBX # copy *EBX to EBX
4561
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#
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b9/copy . . . . . . . a/imm32 # copy to ECX
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ba/copy . . . . . . . 1/imm32/size # copy 1 to EDX
b8/copy . . . . . . . 4/imm32/write # copy 4 to EAX
4581 Even more cuddling. We want to keep lines short where the opcode and operands are self-explanatory. If there are any implicit registers, etc., we'll continue to do the table layout. The first two columns look messy now; let's see how this goes. Maybe I'll give up on the tabular layout altogether, just string args with a single space.
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cd/syscall 0x80/imm8
4456 - example with function calls: factorial I found a bug with multiply in the process; another case (after the swap of call/jump opcodes in 4453) where there's no point improving testing. Unit tests can only tell us if our instructions are internally consistent. Validating against a real machine has to be manual. I'm definitely feeling the pain of debugging machine code now, that's for sure. Going over an instruction trace, comparing the state of registers line by line.
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4561
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# close(stream)
# load stream
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bb/copy . . . . . . . stream/imm32 # copy to EBX
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8b/copy 0/mod/indirect 3/rm32/EBX 3/r32/EBX # copy *EBX to EBX
4561
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#
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b8/copy . . . . . . . 6/imm32/close # copy 6 to EAX
4581 Even more cuddling. We want to keep lines short where the opcode and operands are self-explanatory. If there are any implicit registers, etc., we'll continue to do the table layout. The first two columns look messy now; let's see how this goes. Maybe I'll give up on the tabular layout altogether, just string args with a single space.
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cd/syscall 0x80/imm8
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4561
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# stream = open(filename, O_RDONLY, 0)
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bb/copy . . . . . . . filename/imm32 # copy to EBX
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b9/copy . . . . . . . 0/imm32/rdonly # copy 0 to ECX
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ba/copy . . . . . . . 0x180/imm32/fixed-perms # copy to EDX
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b8/copy . . . . . . . 5/imm32/open # copy 5 to EAX
4581 Even more cuddling. We want to keep lines short where the opcode and operands are self-explanatory. If there are any implicit registers, etc., we'll continue to do the table layout. The first two columns look messy now; let's see how this goes. Maybe I'll give up on the tabular layout altogether, just string args with a single space.
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cd/syscall 0x80/imm8
4561
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# save stream
4535 - support for global variable names
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bb/copy . . . . . . . stream/imm32 # copy to EBX
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89/copy 0/mod/indirect 3/rm32/EBX 0/r32/EAX # copy EAX to *EBX
4561
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# read(stream, b, 1)
# load stream
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bb/copy . . . . . . . stream/imm32 # copy to EBX
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8b/copy 0/mod/indirect 3/rm32/EBX 3/r32/EBX # copy *EBX to EBX
4561
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#
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b9/copy . . . . . . . b/imm32 # copy to ECX
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ba/copy . . . . . . . 1/imm32/size # copy 1 to EDX
b8/copy . . . . . . . 3/imm32/read # copy 3 to EAX
4581 Even more cuddling. We want to keep lines short where the opcode and operands are self-explanatory. If there are any implicit registers, etc., we'll continue to do the table layout. The first two columns look messy now; let's see how this goes. Maybe I'll give up on the tabular layout altogether, just string args with a single space.
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cd/syscall 0x80/imm8
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4561
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# close(stream)
# load stream
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bb/copy . . . . . . . stream/imm32 # copy to EBX
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8b/copy 0/mod/indirect 3/rm32/EBX 3/r32/EBX # copy *EBX to EBX
4561
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#
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b8/copy . . . . . . . 6/imm32/close # copy 6 to EAX
4581 Even more cuddling. We want to keep lines short where the opcode and operands are self-explanatory. If there are any implicit registers, etc., we'll continue to do the table layout. The first two columns look messy now; let's see how this goes. Maybe I'll give up on the tabular layout altogether, just string args with a single space.
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cd/syscall 0x80/imm8
4530 - create an apps/ directory
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4561
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# unlink(filename)
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bb/copy . . . . . . . filename/imm32 # copy to EBX
b8/copy . . . . . . . 0xa/imm32/unlink # copy 10 to EAX
4581 Even more cuddling. We want to keep lines short where the opcode and operands are self-explanatory. If there are any implicit registers, etc., we'll continue to do the table layout. The first two columns look messy now; let's see how this goes. Maybe I'll give up on the tabular layout altogether, just string args with a single space.
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cd/syscall 0x80/imm8
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4561
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# exit(b)
# load b
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bb/copy . . . . . . . b/imm32 # copy to EBX
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8b/copy 0/mod/indirect 3/rm32/EBX 3/r32/EBX # copy *EBX to EBX
4561
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#
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b8/copy . . . . . . . 1/imm32/exit # copy 1 to EAX
4581 Even more cuddling. We want to keep lines short where the opcode and operands are self-explanatory. If there are any implicit registers, etc., we'll continue to do the table layout. The first two columns look messy now; let's see how this goes. Maybe I'll give up on the tabular layout altogether, just string args with a single space.
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cd/syscall 0x80/imm8
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== data
stream:
4564
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00 00 00 00
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a:
4564
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61 00 00 00
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b:
4564
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00 00 00 00
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filename:
4564
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2e 66 6f 6f 00 00 00 00
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# vim:ft=subx:nowrap:tw&