blib_crc_demo.tc

blib_crc_demo.tc — exercise xblib_01_crc via bcall().

Source on GitHub

// blib_crc_demo.tc — exercise xblib_01_crc via bcall().
//
// Prerequisite: upload CRC_BLIB_32.bin to the device's plugin partition
// and `iniz N` it. The firmware logs three "BLIB: registered ..." lines
// at iniz time. After that, the names mb_crc16 / crc32 / crc8_dallas are
// callable from any TinyC slot via `bcall("name", buf, len)`.
//
// Phase-1 bcall signature is locked to (BUF, INT) -> INT — matches the
// CRC primitives this blib exports. Other shapes will be added as more
// blibs ship.

char buf[64];
char msg[80];
int  result;

void EverySecond() {
    // Modbus FC03 read-holding-regs query: slave 1, addr 0, qty 2.
    // Wire bytes (sans CRC): 01 03 00 00 00 02
    buf[0] = 0x01;
    buf[1] = 0x03;
    buf[2] = 0x00;
    buf[3] = 0x00;
    buf[4] = 0x00;
    buf[5] = 0x02;
    result = bcall("mb_crc16", buf, 6);
    sprintf(msg, "blib mb_crc16(01030000 0002) = 0x%04x", result);
    addLog(msg);

    // CRC-32 ISO of the textbook string "123456789" — must equal 0xCBF43926.
    buf[0] = '1'; buf[1] = '2'; buf[2] = '3';
    buf[3] = '4'; buf[4] = '5'; buf[5] = '6';
    buf[6] = '7'; buf[7] = '8'; buf[8] = '9';
    result = bcall("crc32", buf, 9);
    sprintf(msg, "blib crc32('123456789') = 0x%08x  (expected 0xcbf43926)", result);
    addLog(msg);

    // 1-Wire CRC-8 over a fake DS18B20 ROM ID. Result byte fits in
    // the low 8 bits of the int return.
    buf[0] = 0x28; buf[1] = 0xff; buf[2] = 0x11; buf[3] = 0x22;
    buf[4] = 0x33; buf[5] = 0x44; buf[6] = 0x55; buf[7] = 0x66;
    result = bcall("crc8_dallas", buf, 8);
    sprintf(msg, "blib crc8_dallas(28FF...) = 0x%02x", result & 0xff);
    addLog(msg);
}

int main() {
    addLog("blib_crc_demo: every second exercises the bcall syscall");

    // One-shot float ABI check (fcall): the two float args travel to the plugin
    // as raw bits, the plugin does the math, the float returns. On the hard-float
    // P4 this is the end-to-end proof that bit-int float passing works in the
    // TinyC->plugin direction. Scale to millis + integer-compare so the verdict
    // doesn't depend on %f formatting. Expect fadd(2.5,0.25)=2.75, fmul(1.5,4)=6.
    float fa = fcall("fadd", 2.5, 0.25);
    float fm = fcall("fmul", 1.5, 4.0);
    int ia = fa * 1000.0;   // 2750 if the float survived the round trip
    int im = fm * 1000.0;   // 6000
    if (ia == 2750 && im == 6000) {
        addLog("blib fcall FLOAT ABI: PASS (fadd=2.75, fmul=6.0)");
    } else {
        sprintf(msg, "blib fcall FLOAT ABI: FAIL ia=%d im=%d (expect 2750/6000)", ia, im);
        addLog(msg);
    }
    return 0;
}