From a531450447e3526abc415c8d950a5dd654674ec2 Mon Sep 17 00:00:00 2001 From: kitty Date: Sun, 22 Feb 2026 20:48:36 +1100 Subject: starting on assembler nothing functional, mostly my comments as i figure all this out --- jefs.fs | 49 ++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 48 insertions(+), 1 deletion(-) (limited to 'jefs.fs') diff --git a/jefs.fs b/jefs.fs index 1120bfd..63c8c33 100644 --- a/jefs.fs +++ b/jefs.fs @@ -10,7 +10,6 @@ : nip swap drop ; : tuck swap over ; -\ https://wiki.osdev.org/X86-64_Instruction_Encoding Later™ hex : ret, c3 c, ; decimal : cells 8 * ; @@ -19,13 +18,61 @@ hex : ret, c3 c, ; decimal : [compile] parse find drop >cfa compile, ; immediate : ' parse find drop >cfa [compile] lit ; immediate \ note: no error handling (yet) : recurse latest @ >cfa compile, ; immediate + : literal [compile] lit ; immediate : constant create [compile] lit ret, ; : variable 1 cells allot create [compile] lit ret, ; + +\ 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 . 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 ! ; + +: ax 0 ; : cx 1 ; : dx 2 ; : bx 3 ; +: sp 4 ; : bp 5 ; : si 6 ; : di 7 ; +\ at least for now, you have to differentiate these from above +\ by manually setting rex. +: r8 0 ; : r9 1 ; : r10 2 ; : r11 3 ; +: r12 4 ; : r13 5 ; : r14 6 ; : r15 7 ; +\ are there instructions that use registers but Not r/m bytes? +\ i don't actually know + +\ example idea: (from execute below) +\ rex.w rex.r r11 rex.b r14 0 d) mov, +\ rex.w rex.r r14 rex.b r14 8 d) lea, +\ rex.b 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 ] ; \ TODO interpret mode strings? -- cgit v1.2.3