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# Print an error message followed by the text representation of a byte. Then exit.
== code
# 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
# main:
# manual test
#? # . var ed/EAX : exit-descriptor
#? 81 5/subop/subtract 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # subtract from ESP
#? 89/copy 3/mod/direct 0/rm32/EAX . . . 4/r32/ESP . . # copy ESP to EAX
#? # . configure ed to really exit()
#? # . . ed->target = 0
#? c7 0/subop/copy 0/mod/direct 0/rm32/EAX . . . . . 0/imm32 # copy to *EAX
#? # . error-byte(ed, Stdout, msg, 34)
#? 68/push 0x34/imm32
#? 68/push "abc"/imm32
#? 68/push Stderr/imm32
#? 50/push-EAX
#? e8/call error-byte/disp32
# automatic test
e8/call run-tests/disp32 # 'run-tests' is a function created automatically by SubX. It calls all functions that start with 'test-'.
# . syscall(exit, Num-test-failures)
8b/copy 0/mod/indirect 5/rm32/.disp32 . . 3/r32/EBX Num-test-failures/disp32 # copy *Num-test-failures to EBX
b8/copy-to-EAX 1/imm32/exit
cd/syscall 0x80/imm8
# write(out, "Error: "+msg+": "+byte) then stop(ed, 1)
error-byte: # ed : (address exit-descriptor), out : (address buffered-file), msg : (address array byte), n : byte -> <void>
# . prolog
55/push-EBP
89/copy 3/mod/direct 5/rm32/EBP . . . 4/r32/ESP . . # copy ESP to EBP
# write-buffered(out, "Error: ")
# . . push args
68/push "Error: "/imm32
ff 6/subop/push 1/mod/*+disp8 4/rm32/sib 5/base/EBP 4/index/none . . 0xc/disp8 . # push *(EBP+12)
# . . call
e8/call write-buffered/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP
# write-buffered(out, msg)
# . . push args
ff 6/subop/push 1/mod/*+disp8 4/rm32/sib 5/base/EBP 4/index/none . . 0x10/disp8 . # push *(EBP+16)
ff 6/subop/push 1/mod/*+disp8 4/rm32/sib 5/base/EBP 4/index/none . . 0xc/disp8 . # push *(EBP+12)
# . . call
e8/call write-buffered/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP
# write-buffered(out, ": ")
# . . push args
68/push ": "/imm32
ff 6/subop/push 1/mod/*+disp8 4/rm32/sib 5/base/EBP 4/index/none . . 0xc/disp8 . # push *(EBP+12)
# . . call
e8/call write-buffered/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP
# print-byte(out, byte)
# . . push args
ff 6/subop/push 1/mod/*+disp8 4/rm32/sib 5/base/EBP 4/index/none . . 0x14/disp8 . # push *(EBP+20)
ff 6/subop/push 1/mod/*+disp8 4/rm32/sib 5/base/EBP 4/index/none . . 0xc/disp8 . # push *(EBP+12)
# . . call
e8/call print-byte/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP
# write-buffered(out, Newline)
# . . push args
68/push Newline/imm32
ff 6/subop/push 1/mod/*+disp8 4/rm32/sib 5/base/EBP 4/index/none . . 0xc/disp8 . # push *(EBP+12)
# . . call
e8/call write-buffered/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP
# . flush(out)
# . . push args
ff 6/subop/push 1/mod/*+disp8 4/rm32/sib 5/base/EBP 4/index/none . . 0xc/disp8 . # push *(EBP+12)
# . . call
e8/call flush/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP
# stop(ed, 1)
# . . push args
68/push 1/imm32
ff 6/subop/push 1/mod/*+disp8 4/rm32/sib 5/base/EBP 4/index/none . . 8/disp8 . # push *(EBP+8)
# . . call
e8/call stop/disp32
# should never get past this point
$error-byte:dead-end:
# . epilog
89/copy 3/mod/direct 4/rm32/ESP . . . 5/r32/EBP . . # copy EBP to ESP
5d/pop-to-EBP
c3/return
== data
# The buffered file for standard error.
Stderr:
# file descriptor or (address stream)
02 00 00 00 # 1 = standard error
# current write index
00 00 00 00
# current read index
00 00 00 00
# length (8)
08 00 00 00
# data
00 00 00 00 00 00 00 00 # 8 bytes
# TODO: 8 bytes is too small. We'll need to grow the buffer for efficiency. But
# I don't want to type in 1024 bytes here.
# . . vim:nowrap:textwidth=0
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