SPINE-64

The Stack

• Thorn — userland / apps
• Ground — systems C-like language (not yet built)
• SPINE-64 — assembly
• x86-64 — bare metal

Registers

• ret / rax — return value / accumulator
• r1 / rbx — general purpose
• cnt / rcx — counter
• dta / rdx — second return value
• src / rsi — source
• dst / rdi — destination
• r2–r9 — general purpose
• m1, m2 — reserved for processes (kernel cannot touch)

Special registers (compiler managed):

• stp / rsp — stack top pointer
• sbp / rbp — stack base pointer
• sip / rip — stack instruction pointer

Flags

• carry — set if unsigned overflow
• overflow — set if signed overflow
• zero — set if result is exactly 0

Size Specifiers

Appended to memory instructions with dot notation:

• .1 — 1 byte
• .2 — 2 bytes
• .4 — 4 bytes
• .8 — 8 bytes

Example: move.4 ret [0x1000]

Modules

• module code — all code goes here
• module data — all initialized data goes here
• module reserve — all uninitialized data goes here

Alias

Registers can be aliased for readability:

alias reg myCounter

Instructions

Data Movement: move, push, pop, lma (load memory address), swap, movesx (move + sign extend), movezx (move + zero extend)

Arithmetic: add, sub, mul, smul (signed multiply), div, sdiv (signed divide), inc, dec, neg, awc (add with carry), swb (subtract with borrow)

Bitwise: and, or, xor, not, shl, shr, asr, rotl, rotr, racl, racr

Comparison and Jump: cmp with operators: ==, !=, >=, <=, >, < — go label

Functions: fn funcname / fn global funcname / raw fn funcname — call, return, extern

Loops: loop ... end

System: syscall, nope (nop), halt, ioff, ion, pr, pw, int, reti

Addressing Modes

• [0x1000] — fixed address
• [r1] — address in register
• [r1 + 8] — base + fixed offset
• [r1 + r2] — base + register offset
• [r1 + r2 * 4] — base + scaled index
• [r1 + r2 * 4 + 16] — base + scaled index + offset

Example

module data
    message "hello world" 0
    count 0 4

module reserve
    buffer 1024

module code
    fn global main
    start
        lma src message
        move cnt 11
        loop
        start
            move.1 ret [src]
            inc src
            dec cnt
            cmp cnt == 0 go done
        end
        done:
            halt
    end

Binary Output

• Bootloader — flat binary (raw bytes, no header)
• Kernel and userland — ELF format