path: root/03/in02

// open input file
im
--IF
JA
zA
IA
im
##2.
sy
// open output file
im
--OF
JA
im
##241.
IA
im
##1ed.
DA
im
##2.
sy
// read next line
::rl
im
--LI
RA    rbp pointer to line buffer
::rL  read loop
im
##3.  input file descriptor
JA
IR    where to read into
im
##1.
DA    read 1 byte
im
##0.  syscall 0 (read)
sy
// check how many bytes were read
BA
im
##1.
jg   if 1 greater than number of bytes read
:-ef    end of file
BR
DR   pointer to character we just read
im
##1.
+B
RA
BD
zA
lb
BA
im
##a.
jn
:-rL  keep looping
// we now have a full line from the file in ::LI
// the pointer to the end of the line is in rbp
// look at the first character
im
--LI
BA
zA
lb
BA
im
##3b.  ascii ';'
je    if it's a comment,
:-rl  jump back to read the next line
im
##a.  ascii '\n'
je    if it's a blank line,
:-rl  jump back to read the next line
im
##3a.  ascii ':'
je
:-ld   label definition
jm
:-ex
// label definition
::ld
// first, check if we're on the second pass.
im
--2P
BA
zA
lb
BA
zA
jn     if on second pass,
:-rl   ignore this (read next line)
// first get current address
im
##4. output fd
JA
zA
IA   offset = 0
im
##1. whence = SEEK_CUR
DA
im
##8. syscall 8 = lseek
sy
BA
im
##400000. address of start of file
+B
DA   put current address in rdx
im
--L$
BA
lq
JA
im
--LI
IA
// copy from rsi to rdi until a newline is reached
::lc  label copy
BI
zA
lb
BA
// store in rdi
AJ
xc
sb
CA put byte in rcx
// increment rdi,rsi
BJ
im
##1.
+B
JA
BI
im
##1.
+B
IA
BC
im
##a.
jn   if byte we read wasn't a newline,
:-lc keep looping
// store address of label in rdi
AD
BJ
sd
// increment rdi by 4, because we stored an 4-byte number
im
##4.
+B
JA
// now set L$ to rdi
im
--L$
BA
AJ
sq
cc
//
//
// exit with code in rax
::ex
JA
im
##3c.
sy
// convert ASCII hex digit in rbx to number in rax.
::hx
im
##30. compare with ascii '0'
jg
:-bd  bad digit if < '0'
im
##39.
jl
:-af  probably a-f
im
##ffffffffffffffd0.  -48
jm
:-hX
::af
im
##61. ASCII 'a'
jg
:-bd  bad digit (not 0-9, and less than 'a')
im
##66. ASCII 'f'
jl
:-bd  bad digit (not 0-9, and greater than 'f')
im
##ffffffffffffffa9.  -87 (10 - 'a')
::hX
+B
re // return
// bad digit
::bd
im
##2. stderr
JA
im
--BD error message
IA
im
##a. length of error message
DA
im
##1. write
sy
im
##1.
jm
:-ex
// end of file
::ef
// TODO: second pass
zA  exit code 0
jm
:-ex
::2P  second pass?
00
::IF  input file name
'i
'n
'0
'3
00
::OF  output file name
'o
'u
't
'0
'3
00
::BD  bad digit error message
'B
'a
'd
20
'd
'i
'g
'i
't
\n
::LI  line buffer
~~
::L$  end of current label list
--LB
::LB  labels
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