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\ i think something is going on with the stack. i dunno
\ things TODO:
\ EVALUATE
\ CASE
\ DO LOOP
\ <builds does>
\ argc/argv
\ file io
\ interactive input

: cell+  8 + ;
: syswrite ( u c-addr fd -- n )  1 syscall3 ;
: say ( c-addr u -- )  swap 2 syswrite drop ;
: emit ( chr -- )  sp cell+ 1 swap 1 syswrite 2drop ;
: cr  10 emit ;

: decimal  10 base ! ;
: hex  16 base ! ;

: nip  swap drop ;
: tuck  swap over ;

hex : ret,  c3 c, ; decimal

: cells  8 * ;
: allot  here @ swap here +! ;

: [compile]  parse find drop >cfa compile, ; immediate
: '  parse find drop >cfa [compile] lit ; immediate \ note: no error handling (yet)
: recurse  latest @ >cfa compile, ; immediate
: s, ( c-addr u -- )  here @ swap ( c-addr here u ) dup >r cmove r> here +! ;

: literal  [compile] lit ; immediate
: constant  create [compile] lit ret, ;
: variable  1 cells allot create [compile] lit ret, ;

\ jump helpers from forth83 (got them from pforth tho ehehe)
\ < backward jump  > forward jump
\ adding/subtracting 4 gets to the next instruction.
: <mark  here @ ;
: <resolve  here @ 4 + - d, ;
: >mark  here @ 0 d, ;
: >resolve  dup here @ swap - 4 - swap d! ;

: begin  <mark ; immediate
: again  branch <resolve ; immediate
: until  ?branch <resolve ; immediate
: if  ?branch >mark ; immediate ( I: -- a )
: else  branch >mark swap >resolve ; immediate
: then  >resolve ; immediate
: while  ?branch >mark ; immediate
: repeat  branch swap <resolve >resolve ; immediate

: ?dup  dup 0<> if dup then ;

\ TODO interpret mode strings?
\ i think s" causes stack underflow
: s"  1 >in +! [ char " ] literal cparse branch >mark >r 2dup cmove, r> >resolve swap [compile] lit [compile] lit ; immediate
: ."  [compile] s" ' say compile, ; immediate \ lol this word breaks the highlighting, here have another "

\ https://wiki.osdev.org/X86-64_Instruction_Encoding
\ see dusk os asm/x86.fs
\ my idea is that operands are given in the reverse order that
\ they are in intel notation, so that intel notation can be vaguely
\ turned into this assembler by moving the mnemonic to the end,
\ like: mov r11, r12  ->  smth like r11 r12 mov,
\ a lot of this would probably be more elegant but i have to get around
\ to <builds and does>. i don't want to have to
hex
variable rex
variable modrm

: asm$  0 rex ! c0 modrm ! ;

: rex.w  rex @ 48 or rex ! ;
: rex.r  rex @ 44 or rex ! ;
: rex.x  rex @ 42 or rex ! ;
: rex.b  rex @ 41 or rex ! ;
: rex,  rex @ ?dup if c, then ;

\ REGISTERS {{{
: rax  modrm @ 0 or modrm ! ; : rcx  modrm @ 1 or modrm ! ;
: rdx  modrm @ 2 or modrm ! ; : rbx  modrm @ 3 or modrm ! ;
: rsp  modrm @ 4 or modrm ! ; : rbp  modrm @ 5 or modrm ! ;
: rsi  modrm @ 6 or modrm ! ; : rdi  modrm @ 7 or modrm ! ;
: r8   modrm @ 0 or modrm ! rex.b ; : r9   modrm @ 1 or modrm ! rex.b ;
: r10  modrm @ 2 or modrm ! rex.b ; : r11  modrm @ 3 or modrm ! rex.b ;
: r12  modrm @ 4 or modrm ! rex.b ; : r13  modrm @ 5 or modrm ! rex.b ;
: r14  modrm @ 6 or modrm ! rex.b ; : r15  modrm @ 7 or modrm ! rex.b ;

: rax,  modrm @ 00 or modrm ! ; : rcx,  modrm @ 08 or modrm ! ;
: rdx,  modrm @ 10 or modrm ! ; : rbx,  modrm @ 18 or modrm ! ;
: rsp,  modrm @ 20 or modrm ! ; : rbp,  modrm @ 28 or modrm ! ;
: rsi,  modrm @ 30 or modrm ! ; : rdi,  modrm @ 38 or modrm ! ;
: r8,   modrm @ 00 or modrm ! rex.r ; : r9,   modrm @ 08 or modrm ! rex.r ;
: r10,  modrm @ 10 or modrm ! rex.r ; : r11,  modrm @ 18 or modrm ! rex.r ;
: r12,  modrm @ 20 or modrm ! rex.r ; : r13,  modrm @ 28 or modrm ! rex.r ;
: r14,  modrm @ 30 or modrm ! rex.r ; : r15,  modrm @ 38 or modrm ! rex.r ;
\ }}}

: /0  modrm @ 00 or modrm ! ; : /1  modrm @ 08 or modrm ! ;
: /2  modrm @ 10 or modrm ! ; : /3  modrm @ 18 or modrm ! ;
: /4  modrm @ 20 or modrm ! ; : /5  modrm @ 28 or modrm ! ;
: /6  modrm @ 30 or modrm ! ; : /7  modrm @ 38 or modrm ! ;

\ TODO store and write the displacement if given
: mod0  modrm @ 3f and modrm ! ;
: d)  mod0 0<> if modrm @ 40 or modrm ! then ; \ disp8 or 0 only for now

: mov,  rex, 8b c, modrm @ c, asm$ ;

\ example idea: (from execute below)
\ rex.w r11, r14 0 d) mov,
\ rex.w r14, r14 8 d) lea,
\ r11 call,
decimal

: execute  [ hex
	4d c, 8b c, 1e c, \ mov r11, [r14]
	\ REX.W + 8B /r  --  MOV r64, r/m64
	\ rex w (64 bit operand size), r (modrm.reg ext), b (modrm.rm ext)
	\ modrm 00 011 110
	\ mod [r/m]  reg 1.011 (r11)  r/m 1.110 (r14)
	4d c, 8d c, 76 c, 08 c, \ lea r14, [r14+8]
	\ REX.W + 8D /r  --  LEA r64, m
	\ rex w (64 bit operand size), r (modrm.reg ext), b (modrm.rm ext)
	\ modrm 01 110 110
	\ mod [r/m+disp8]  reg 1.110 (r14)  r/m 1.110 (r14)
	41 c, ff c, d3 c, \ call r11
	\ FF /2  --  CALL r/m64
	\ rex b (.rm ext)
	\ modrm 11 010 011
	\ mod r/m  reg /2   r/m 1.011 (r11)
	decimal ] ;

: /  /mod swap drop ;
: mod  /mod drop ;
: negate  0 swap - ;
: abs  dup 0< if negate then ;

32 constant bl
: space  bl emit ;
: spaces  begin dup 0> while space 1- repeat drop ;

\ PNO
\ mostly from pforth
255 allot variable pad drop
variable hld
: <#  pad hld ! ;
: hold  1 hld -! ( chr ) hld @ c! ;
: sign  0< if [ char - ] literal hold then ;
: #  base @ /mod swap 9 over > if 7 + then [ char 0 ] literal + hold ;
: #s  begin # dup 0= until ;
: #>  drop hld @ pad over - ;

: (u.)  <# #s #> ;
: u.  (u.) say space ;
: u.r  >r (u.) r> over - spaces say ;

: (.)  dup abs <# #s swap sign #> ;
: . (.)  say space ;
: .r  >r (.) r> over - spaces say ;

: (.byte)  hex <# # # #> decimal ;
: .byte  (.byte) say space ;
: (.word)  hex <# # # # # #> decimal ;
: .word  (.word) say space ;
: (.dword)  hex <# # # # # # # # # #> decimal ;
: .dword  (.dword) say space ;
: (.qword)  hex <# # # # # # # # # # # # # # # # # #> decimal ;
: .qword  (.qword) say space ;

: ?  @ . ;
: .s  sp 8 + ( skip sp itself ) begin dup s0 @ > while dup @ .qword 8 + repeat drop cr ;
: bytes-allocated  hend @ h0 @ - ;
: bytes-used  here @ h0 @ - ;
: bytes-free  bytes-allocated bytes-used - ;
: .free  bytes-free u. ." of " bytes-allocated u. ." bytes free (used " bytes-used (.) say ." )" cr ;

: >ffa ( lfa -- ffa )  8 + ;
: >nfa ( lfa -- nfa )  9 + ;
: (words) ( lfa -- )  >nfa dup w@ swap 2 + swap say 2 spaces ;
: words  latest @ begin ?dup 0<> while dup (words) @ repeat cr ;

\ TODO causes segfault i think when switching back?
: (evaluate) ( c-addr u -- )  0 >in ! ( u ) #tib ! ( c-addr ) tib ! interpret ;
: evaluate ( c-addr u -- ) >r >r tib @ #tib @ >in @ r> r> (evaluate) >in ! #tib ! tib ! ;
\ maybe the old TIB should be on retstack
\ so stack undeflows don't fuck with INTERPRET

\ : teststr3 s" 1 2 3 .s" ;
\
\ teststr3 evaluate
.free
bye