== Getting Started

=== Setting Up the Toolchains

JoeyLib cross-compiles for five machines, and every cross toolchain lives under
`toolchains/` in the repository. They are fetched and built once:

[source,console]
----
$ ./toolchains/install.sh
----

Then, *in every shell session before you build anything*:

[source,console]
----
$ source toolchains/env.sh
----

[WARNING]
====
Forgetting `source toolchains/env.sh` is the single most common build problem.
The makefiles reference the cross compilers only through the variables that
script sets, so without it a build can appear to succeed while producing stale
or missing binaries, and errors are reported as `Error 127 (ignored)`. If a
build behaves strangely, source the script and try again.
====

Check what the build can see:

[source,console]
----
$ make status
Toolchain availability:
  iigs:    yes
  amiga:   yes
  atarist: yes
  dos:     yes
----

=== Building

[source,console]
----
$ make                 # every target whose toolchain is present
$ make iigs            # Apple IIgs only
$ make amiga           # Commodore Amiga only
$ make atarist         # Atari ST only
$ make dos             # MS-DOS only
$ make clean           # remove all build outputs
----

The X68000 port has its own makefile:

[source,console]
----
$ make -f make/x68000.mk
----

Built programs land under `build/<platform>/bin/`. The IIgs additionally
produces a bootable disk image:

[source,console]
----
$ make iigs-disk       # build/iigs/bin/joey.2mg
----

[TIP]
====
Never judge a retro build by its exit status alone. Check that the file you
expect actually appeared and has a recent timestamp. `make iigs` builds the
library but *no examples* -- `make iigs-disk` is what builds and packages them.
====

=== Hello, JoeyLib

The smallest complete program. This is `examples/hello/hello.c`:

[source,c]
----
#include <stdio.h>
#include <joey/joey.h>

int main(void) {
    jlConfigT config;

    config.codegenBytes = 8 * 1024;
    config.audioBytes   = 64UL * 1024;

    if (!jlInit(&config)) {
        fprintf(stderr, "jlInit failed: %s\n", jlLastError());
        return 1;
    }

    printf("JoeyLib %s\n", jlVersionString());
    printf("Platform: %s\n", jlPlatformName());
    printf("Hello from JoeyLib.\n");

    jlShutdown();
    return 0;
}
----

Three things to notice, because they apply to every JoeyLib program:

. *One header.* `#include <joey/joey.h>` pulls in everything except the
  optional serial add-on.
. *`jlInit` can fail*, and when it does `jlLastError()` tells you why. Always
  check it.
. *`jlShutdown` is not optional.* It restores the display mode, releases the
  Memory Manager blocks or DOS memory the library took, and on several ports
  un-hooks interrupt vectors. Skipping it can leave the machine in an unusable
  state.

=== Something on the Screen

`hello.c` prints text but never draws. Here is the smallest program that puts
graphics on screen and waits for a keypress:

[source,c]
----
#include <joey/joey.h>

int main(void) {
    jlConfigT   config;
    jlSurfaceT *stage;
    uint16_t    colors[SURFACE_COLORS_PER_PALETTE];
    uint8_t     i;

    config.codegenBytes = 8 * 1024;
    config.audioBytes   = 0;
    if (!jlInit(&config)) {
        return 1;
    }

    stage = jlStageGet();               // the library-owned back buffer

    // Build palette 0. Entry 0 is forced black whatever we put here.
    for (i = 0; i < SURFACE_COLORS_PER_PALETTE; i++) {
        colors[i] = 0x000;
    }
    colors[1] = 0xFFF;                  // white
    colors[2] = 0xF00;                  // red
    colors[3] = 0x00F;                  // blue
    jlPaletteSet(stage, 0, colors);

    // Every scanline uses palette 0 (this is also the default).
    jlScbSetRange(stage, 0, SURFACE_HEIGHT - 1, 0);

    jlSurfaceClear(stage, 0);
    jlFillRect(stage, 40, 30, 240, 140, 3);
    jlDrawRect(stage, 40, 30, 240, 140, 1);
    jlDrawLine(stage, 0, 0, SURFACE_WIDTH - 1, SURFACE_HEIGHT - 1, 2);

    jlStagePresent();                   // nothing is visible until this runs
    jlWaitForAnyKey();

    jlShutdown();
    return 0;
}
----

The critical line is `jlStagePresent()`. All drawing goes to an off-screen
back buffer called the *stage*; nothing reaches the display until you present.

=== Running What You Built

Helper scripts boot each target in an emulator:

[source,console]
----
$ scripts/run-iigs.sh DRAW
$ scripts/run-amiga.sh Draw
$ scripts/run-atarist.sh DRAW
$ scripts/run-dos.sh DRAW
$ scripts/run-x68000.sh DRAW
----

Note the capitalisation differences: the IIgs, ST and DOS use uppercase names
(ProDOS, GEMDOS and DOS 8.3 conventions), while the Amiga keeps mixed case.

=== The Example Programs

The `examples/` directory is the best available reference, and every example is
built for every platform:

[cols="1,4", options="header"]
|===
|Example |What it shows

|`hello`     |Minimal init, version query, shutdown.
|`draw`      |Every drawing primitive, laid out in four quadrants.
|`pattern`   |Palette and per-scanline palette (SCB) work.
|`keys`      |Typed-character input and the key predicates.
|`joy`       |Joystick axes, buttons and recalibration.
|`sprite`    |Sprite loading, compiling, save-under and restore.
|`audio`     |Tracker music, `.MOD` playback and digital sound effects.
|`save`      |Save files and the disk-space query.
|`serial`    |The optional RS-232 add-on.
|`adventure` |A small complete game.
|`agi`       |A Sierra AGI interpreter, showing the library under real load.
|`spacetaxi` |A full port of Space Taxi: the largest example.
|`uber`      |The validation and benchmark harness.
|===