116 lines
4.8 KiB
Plaintext
116 lines
4.8 KiB
Plaintext
## port of https://github.com/akkartik/crenshaw/blob/master/tutor2.1.pas
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# corresponds to the section "single digits" in https://compilers.iecc.com/crenshaw/tutor2.txt
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#
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# To run (from the subx directory):
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# $ subx translate *.subx apps/crenshaw2.1.subx -o crenshaw 2.1
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# $ echo '3' |subx run apps/crenshaw2.1 |xxd -
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# Expected output:
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# TODO
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#
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# The output is the code a function would need to include, returning the
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# result in EAX.
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#
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# Major note: byte strings are not null-terminated. Instead they're prefixed
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# with a 32-bit length.
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== code
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# instruction effective address operand displacement immediate
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# op subop mod rm32 base index scale r32
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# 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
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# main:
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# abort("Integer")
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# push args
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68/push "Integer"/imm32
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# call
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e8/call abort/disp32
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# discard arg
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81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP
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# exit(0)
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bb/copy-to-EBX 0/imm32
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b8/copy-to-EAX 1/imm32/exit
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cd/syscall 0x80/imm8
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## helpers
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# print error message and exit
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# really maps to the 'Expected' function in Crenshaw
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abort: # s : (address array byte) -> <void>
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# error(s)
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# push args
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ff 6/subop/push 1/mod/*+disp8 4/rm32/sib 4/base/ESP 4/index/none . . 4/disp8 . # push *(ESP+4)
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# call
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e8/call error/disp32
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# discard arg
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81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP
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# exit(1)
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bb/copy-to-EBX 1/imm32
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b8/copy-to-EAX 1/imm32/exit
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cd/syscall 0x80/imm8
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# print out "Error: #{s} expected\n" to stderr
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error: # s : (address array byte) -> <void>
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# write-stderr("Error: ")
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# push args
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68/push "Error: "/imm32
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# call
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e8/call write-stderr/disp32
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# discard arg
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81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP
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# write-stderr(s)
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# push args
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ff 6/subop/push 1/mod/*+disp8 4/rm32/sib 4/base/ESP 4/index/none . . 4/disp8 . # push *(ESP+4)
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# call
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e8/call write-stderr/disp32
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# discard arg
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81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP
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# write-stderr(" expected")
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# push args
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68/push " expected"/imm32
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# call
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e8/call write-stderr/disp32
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# discard arg
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81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP
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# write-stderr("\n")
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# push args
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68/push Newline/imm32
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# call
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e8/call write-stderr/disp32
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# discard arg
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81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP
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# end
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c3/return
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write-stdout: # s : (address array byte) -> <void>
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# prolog
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55/push-EBP
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89/copy 3/mod/direct 5/rm32/EBP . . . 4/r32/ESP . . # copy ESP to EBP
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# save registers
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50/push-EAX
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51/push-ECX
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52/push-EDX
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53/push-EBX
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# write(1/stdout, (data) s+4, (size) *s)
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# fd = 1 (stdout)
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bb/copy-to-EBX 1/imm32
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# x = s+4
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8b/copy 1/mod/*+disp8 4/rm32/sib 5/base/EBP 4/index/none . 1/r32/ECX 8/disp8 . # copy *(EBP+8) to ECX
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81 0/subop/add 3/mod/direct 1/rm32/ECX . . . . . 4/imm32 # add to ECX
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# size = *s
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8b/copy 1/mod/*+disp8 4/rm32/sib 5/base/EBP 4/index/none . 2/r32/EDX 8/disp8 . # copy *(EBP+8) to EDX
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8b/copy 0/mod/indirect 2/rm32/EDX . . . 2/r32/EDX . . # copy *EDX to EDX
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# call write()
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b8/copy-to-EAX 4/imm32/write
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cd/syscall 0x80/imm8
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# restore registers
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5b/pop-to-EBX
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5a/pop-to-EDX
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59/pop-to-ECX
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58/pop-to-EAX
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# end
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89/copy 3/mod/direct 4/rm32/ESP . . . 5/r32/EBP . . # copy EBP to ESP
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5d/pop-to-EBP
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c3/return
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# vim:nowrap:textwidth=0
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