Diff — ALB FASM backend

{{infobox

| title = ALB FASM backend

| target_flag = `-t fasm`

| produces = x86-64 Flat Assembler source (.asm)

| output = Windows PE64 — console, GUI, or DLL

| assembler = [Flat Assembler](https://flatassembler.net) (fasm.exe)

| emitter_unit = `Emit_Native_FASM` (emit_native_fasm.adb)

| status = Primary native backend; `--build` supported

}}

The **ALB FASM backend** is [[AdaLogic BASIC]]'s flagship native emitter: it turns an ALB program into **x86-64 assembly source** for the [Flat Assembler](https://flatassembler.net), which then assembles — in a single pass, in milliseconds — into a real Windows PE64 executable with no linker and no C runtime requirement beyond what ALB brings itself.

```alb One-liner

albt hello.alb -t fasm --build

→ fasm_hello/hello.asm → fasm.exe → hello.exe (a few kilobytes, instantly)

```

It is one of only three backends — with [[ALB C backend|C]] and [[ALB FASM16 backend|FASM16]] — where `--build` is supported end to end: the compiler emits the file **and** drives the assembler.

## What it produces

Every generated file opens the same way — a comment banner, then the PE64 header:

```text

; ==========================================================

; GENERATED BY ADALOGIC BASIC (ALB) TRANSPILER

; TARGET: x64 FASM (Bare-Metal PE Executable)

; ==========================================================

format PE64 Console

stack 1000000h

heap 1000000h

entry start

include 'win64a.inc'

```

The emitter supports three output formats, switched by flags such as `--dll`:

| Format | Emitted header | Result |

| --- | --- | --- |

| Console | `format PE64 Console` | Command-line .exe — the default |

| GUI | `format PE64 GUI` | Windowed .exe — no console |

| DLL | `format PE64 DLL at 10000000h` | Shared library with an ALB export entry |

Console and GUI builds reserve a **16 MiB stack and 16 MiB heap** (`stack 1000000h / heap 1000000h`) — generous headroom for recursion and the temporal-state system, at zero runtime cost since Windows commits the pages lazily.

## The file anatomy

A FASM output is organized into the classic PE sections:

- **`.text`** — code: the runtime library, then your program under `start:`

- **`.data`** — initialized writable data: string literals, buffers, the GC grid

- **`.bss`** — zero-initialized storage

- **`.idata`** — imports: only the Win32 functions actually used (printf, ExitProcess, GDI, winsock…)

- **`.reloc`** — relocations, emitted for DLL builds

## The macro layer — FASM as co-optimizer

Here is the part that surprises people. The emitter writes expressions in a deliberately simple infix-looking style — `mov rax, a + mov rax, b` — and then defines an `ALB_LET` macro that uses FASM's `match` directive to **rewrite those patterns into optimized code at assembly time**:

```text

match =0 =mov =rax, dest, =mov =rax, a + =mov =rax, b, matched line {

    mov rax, a

    add rax, b

    mov dest, rax

    define matched 1

  }

```

The assembler itself pattern-matches each emitted statement and fuses the verbose three-instruction form into a tight `mov/add/mov`. The compiler stays simple; the assembler does the peephole optimization. Two tools, each doing what it's best at.

Alongside it, `ALB_MASK_OP` provides **branchless selection** — a conditional computed as a bitmask (`neg / and / not / and / or`) instead of a jump, for the constant-time code paths where a branch would be unpredictable or unsafe.

## The hardened runtime

ALB does not trust the machine blindly — the emitted program carries a safety runtime:

```text

ALB_Runtime_Trap_DivZero:

  sub rsp, 40

  invoke printf, ALB_Runtime_DivZero

  invoke ExitProcess, 1

```

Divide by zero, index out of bounds, or leave a declared range and the program *reports and halts* rather than corrupting onward — the Ada philosophy showing through the BASIC surface. Every runtime routine is wrapped in FASM's `if used … end if`, so **the assembler strips everything your program never calls**: a hello world links in almost none of the library below.

And the library is large:

- **Strings** — `ALB_Str_Eq`, `Mid/Left/Right`, `ALB_Hash`, length/copy/concat with fixed-capacity vaults

- **Console** — prompts, buffered input with a hand-rolled S64 parser (`ALB_Input_Try_Parse_S64`, whitespace and sign handled in raw asm)

- **Files** — open/read/write/close/len/seek, plus `ALB_OS_Load`/`ALB_OS_Flush` whole-file vaults

- **Math** — sqrt/sine/cosine/abs, random, and the **PURE** engine (`ALB_Pure_Add/Sub/Mul/Div/Pow`) — exact rational arithmetic with numerator and denominator kept separate, so ⅓ + ⅓ stays exactly ⅓

- **Graphics & sound** — Win32 window creation, message loop, put-pixel, BGR colors, key and mouse state, music buffer streaming

- **Data formats** — a complete **FITS** astronomy file reader (card loop, BITPIX parsing, NAXIS) and an **INI** parser — emitted only if used

- **FFI** — `ALB_Load_Foreign_Symbol` loads DLL functions at runtime; ALB's `IMPORT_DLL` lowers to direct calls

```fact The odd superpowers

```

## The learning runtime — forged by the compiler

`MARKOV MODEL`, `PREDICT MARKOV`, `NEURAL TOPOLOGY`, `INFER NETWORK`, and `TRAIN NETWORK` aren't library calls — they're **language-level statements** with their own AST node kinds. When `albt` sees one, it registers the model in compile-time tables (up to **128 Markov models** and 32,768 transition weights; up to **64 neural topologies** sharing 512 layer slots), bakes the declared matrices straight into `.data`, and flips a `Runtime_Used` flag. Then the compiler's own **Phase 4.5 — "Forging FASM Extended Runtime"** — appends only the runtimes that were actually requested:

- **`ALB_Markov_Predict:`** — a ~30-instruction argmax: index the transition-matrix row for the current state, walk it once, return the likeliest next state

- **`ALB_NN_Apply_Activation:`** — activation by code: linear, ReLU, step, and a clamped ±128→×8 scaled tanh — all integers

- **`ALB_NN_Infer:`** — a pure-integer forward pass over a meta-descriptor of layer sizes, offsets, weights, and biases

- **`ALB_NN_Train:`** — a perceptron-style delta rule (`delta ∈ {-1, 0, +1}`: nudge the bias, nudge each weight where the input fired) refining the output layer per epoch

And the weights themselves are *seeded by the compiler*: `Seed_Neural_Weight` in `albt` assigns deterministic structured guesses — identity patterns for same-size layers (weight 256 = 1.0 at ¹⁄₂₅₆ scale), +256/−256 split-pairs when a layer halves, wrap-around when it grows. No RNG; the same program always starts from the same brain.

```warn FASM-only: EMOTION

```

## Concurrency, honestly stated

`SPAWN` on this backend is documented in the emitter's own words as *"synchronous on FASM (same-core call)"* — and `SYNC`/`ATOMIC` lower to `mfence`. The honesty matters: the multi-core dispatch is real on the [[ALB C backend]], deliberately sequential here.

## The blackbox

`--embed-blackbox` installs a **VEH crash reporter** — a vectored exception handler and a heap-free append-only dump path (`ALB_BB_Append_Z`, `ALB_Blackbox_Handler`) that writes a forensic record when a native fault would otherwise vanish silently. A flight recorder for the generated executable, compiled in only when asked for.

## Under the hood — the emitter itself

The backend is the Ada package `Emit_Native_FASM` (~7,300 lines, SPARK-annotated). Its design is a small lesson in compiler construction:

- **Two text buffers** — `Buffer_Global` (lands in `.data`/`.bss`) and `Buffer_Main` (lands in `.text`) — so declarations and code accumulate independently and merge at flush time

- **A stable Emit_* API** — `Emit_If_Start`, `Emit_For_Start`, `Emit_BinOp`… The same call surface every backend implements, which is how one front end drives ~23 targets

- **Expression scrubbing** — before emitting an operator the emitter backspaces trailing newlines so infix text lands on one line, which is what makes the `ALB_LET` match-macro possible

```note Where it lives

In the source tree: `EMITTER/emit_native_fasm.adb`, driven by `albt.adb`. Emitted sources land in `fasm_<name>/` by default. The whole toolchain is Apache 2.0.

```

## See also

- [[AdaLogic BASIC]] — the language this emits

- [[ALB FASM16 backend]] — its 16-bit sibling

- [[ALB C backend]] — the portable sibling

- [[History of Programming]] — where assemblers fit in the long arc

- [[Konrad Zuse]] · [[Z3]] · [[Plankalkül]] — the other end of that arc

[[Category:Backends]]

[[Category:AdaLogic BASIC]]