; The assembler's front end on its own, one line per token.
;
; Prints the line each token started on, what the token turned out to be, how many bytes
; it will come to, and the token itself between brackets so that whitespace at either end
; would show if any ever leaked in.
;
; WHAT A TOKEN IS is the part worth checking here rather than at the far end. A wrong
; classification does not produce a wrong byte in an obvious place - it produces a right
; looking program of the wrong length, with everything after it shifted, and by then the
; only symptom is that a label points at the middle of an instruction.
;
; Written by Anachronaut

#Include services.asm

#Program

  #Base 0x2000

start:
  SETD.0 Wanted
  INIB 0d23
  SWI osArgument
  SETD.0 Wanted
  LDA.0
  BRA nothingAsked

  SETD.0 Wanted
  CALL srcOpen
  BNQ noFile

tokenLoop:
  CALL tokNext
  BNQ tokensDone

  SETD.0 TokLine
  LDA.0
  INCD.0
  LDB.0
  SWI osPrintNumber

  CALL clsToken
  BNQ badToken

  ; Which of the six it turned out to be. The names are four characters and a space, so
  ; the columns line up without any counting.
  SETD.0 TypeNames
  SETD.2 ClsType
  LDA.2
  CALL nameOfType
  SETD.1 NamePointer
  LDD.0.1
  SWI osPrintString

  SETD.0 ClsLength
  LDA.0
  RSTB
  PSHA
  POPB
  RSTA
  SWI osPrintNumber

  SETD.0 OpenMark
  SWI osPrintString
  SETD.0 TokText
  SWI osPrintString
  SETD.0 CloseMark
  SWI osPrintString
  BRI tokenLoop

badToken:
  SETD.0 StoppedText
  SWI osPrintString
  SWI osExit

; The name of type A, out of a table of fixed width entries so that no pointer arithmetic
; is needed beyond a multiply by the width.
nameOfType:
  SETD.0 TypeWidth
  LDB.0
  RSTA
  SETD.0 NameLeft
  STA.0
  SETD.2 ClsType
  LDA.2
  SETD.0 NameOffset
  CALL numZero
nameLoop:
  SETD.2 ClsType
  LDA.2
  SETD.0 NameLeft
  LDB.0
  CCF
  SUB
  BRQ nameFound
  SETD.0 TypeWidth
  LDA.0
  SETD.0 NameOffset
  CALL numAddByte
  SETD.0 NameLeft
  LDA.0
  INCA
  STA.0
  BRI nameLoop
nameFound:
  ; The answer is left in NamePointer rather than in DP0, because a RET puts Data Pointers
  ; 0 to 2 back as they were: a routine cannot hand back a pointer, only write one down.
  SETD.0 TypeNames
  SETD.1 NamePointer
  STD.0.1
  SETD.0 NamePointer
  SETD.2 NameOffset
  CALL numAdd
  RET

tokensDone:
  SETD.0 DoneText
  SWI osPrintString
  SWI osExit

nothingAsked:
  SETD.0 AskText
  SWI osPrintString
  SWI osExit

noFile:
  SETD.0 NoFileText
  SWI osPrintString
  SWI osExit

#Data

  #Base 0x1000

Wanted:
  #Reserve 0d23

OpenMark:
" ["
CloseMark:
"]
"
; Six names of eleven characters each, counting the zero the assembler puts on the end of
; every string. Written one to a line so that adding a type is adding a line.
TypeNames:
"  keyword "
"  instr   "
"  value   "
"  string  "
"  label:  "
"  label   "
TypeWidth:
  0d11
NameLeft:
  0x00
NameOffset:
  0x00 0x00
NamePointer:
  0x00 0x00

StoppedText:
"---- stopped: the assembler does not understand that
"
DoneText:
"---- no more tokens
"
AskText:
"say which file
"
NoFileText:
"no such file
"

#Include numbers.asm
#Include source.asm
#Include token.asm
#Include classify.asm
#Include table.asm