tinclib

Wi-Fi, HTTP and HTTPS for TI-84 Plus CE programs. Plug an ESP8266 board into the calculator's USB port and your C or C++ program can fetch web pages, call REST APIs and upload data.

• HTTP and HTTPS: GET, POST, PUT, PATCH, DELETE and HEAD, with certificate checking, request headers and response headers.
• Small: no malloc, static buffers sized at compile time, and the linker drops what you don't call (about 4 KB for a connection check, 10 KB for the whole API).
• Simple: one request at a time, driven by tinc_poll() from your main loop. No handles to free.
• Wi-Fi setup handled for you: tinc_openConfig() hands off to the TINCLIBC config app.
• C and C++: tinclib.hpp adds header-only bindings with no exceptions and no allocation.
• Tested: host unit tests (ASan/UBSan, gcc and clang) against a fake board, CEmu tests, and real hardware.

tinclib is one part of four:

You need a TI-84 Plus CE, an ESP8266 board whose USB bridge is CDC, FTDI or PL2303 (the calculator's USB driver doesn't support CP210x or CH340), and the CE C/C++ Toolchain to build.

#include "tinclib.h"

static const tinc_config_t cfg = { "MYAPP", 0, TINC_CF_ASCII };
tinc_request_t req = { TINC_GET, "http://example.com/", NULL, NULL, 0 };
tinc_state_t st;
char buf[64];

if (tinc_init(&cfg) == TINC_OK && tinc_isActive(TINC_WIFI) && tinc_request(&req) == TINC_OK)
    while ((st = tinc_poll()) != TINC_DONE && st != TINC_ERROR) {
        int16_t n = tinc_read(buf, sizeof buf);
        /* use n bytes */
    }
tinc_shutdown();

src/tinclib.h is the whole API, with the details. In short:

• One request at a time. tinc_request() starts it, tinc_poll() drives it (call it from your main loop), tinc_read() copies out the body.
• No malloc. Buffers are static and sized at compile time (TINC_RX_BUF_SIZE).
• tinc_openConfig() sends the user to TINCLIBC. Your program is unloaded and starts over from main() afterwards, so save your state first. tinc_init() then tells you whether setup worked.
• Protocol 0.7: GET, POST, PUT, PATCH, DELETE and HEAD over http:// or https://. A request body is streamed from your buffer, not copied, so keep it untouched until the state reaches TINC_BODY. tinc_header() reads a response header (e.g. Location). HTTPS certificates are always checked against CA roots built into the board's firmware (TLS 1.2 at most). The board's firmware must speak the same protocol version (0.7): until 1.0, a mismatch fails tinc_init() with TINC_ERR_VERSION.

See examples/hello/ for a complete program.

Download tinclib-vX.Y.Z.zip from the releases, unzip it into your CEdev project's lib/ folder, and add to your makefile:

CFLAGS = -Wall -Wextra -Oz -Ilib/tinclib/src
EXTRA_C_SOURCES = $(wildcard lib/tinclib/src/*.c)

The library is compiled into your program, and the linker leaves out what you don't call (make size-check verifies it: a program that only checks the connection is about half the size of one using everything). The calculator needs the CE C libraries usbdrvce, srldrvce and fileioc.

tinclib.h works from C++ as is. tinclib.hpp adds thin, header-only bindings: the same calls in namespace tinc, enum classes for states and methods, and a tinc::Session that calls tinc_init() and, when it goes out of scope, tinc_shutdown(). No exceptions, no allocation; errors are return codes as in C. Add -Ilib/tinclib/src to CXXFLAGS.

#include "tinclib.hpp"

tinc::Session net({ "MYAPP", 0, TINC_CF_ASCII });
if (net.err() == tinc::Ok && tinc::isActive() &&
    tinc::request(tinc::Method::Get, "https://example.com/") == tinc::Ok) {
    char buf[64];
    tinc::State st;
    while ((st = tinc::poll()) != tinc::State::Done && st != tinc::State::Error) {
        int16_t n = tinc::read(buf);   // size taken from the array
        // use n bytes of buf
    }
}

See CONTRIBUTING.md to build and test tinclib itself.

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