Register browser

This advanced example reads a few hardware registers and prints their values. It is inspired by the register browser in Lephenixnoir/gintctl on the Planet Casio git forge.

Direct register access is useful when debugging drivers, clocks, interrupts, and low-level hardware state. It is also easy to misuse, so this example only reads registers.

What it shows

• Including gint/mpu/* headers
• Reading interrupt, power and clock registers
• Reading the CPU cache control register with a volatile pointer
• Displaying raw hexadecimal values

Full source

#define FXCP
#include <stdint.h>
#include <gint/display.h>
#include <gint/keyboard.h>
#include <gint/mpu/intc.h>
#include <gint/mpu/power.h>
#include <gint/mpu/cpg.h>

int main(void)
{
    while(1) {
        dclear(C_WHITE);

        dtext(8, 8, C_BLACK, "Register browser");
        dtext(8, 28, C_BLACK, "Read-only hardware state");
        dtext(8, 48, C_BLACK, "Press EXIT to leave");

        dprint(8, 90, C_BLACK, "IPRA: %04x", SH7305_INTC._->IPRA.word);
        dprint(8, 110, C_BLACK, "IPRB: %04x", SH7305_INTC._->IPRB.word);
        dprint(8, 130, C_BLACK, "IPRC: %04x", SH7305_INTC._->IPRC.word);
        dprint(8, 150, C_BLACK, "IPRD: %04x", SH7305_INTC._->IPRD.word);

        dprint(8, 190, C_BLACK, "MSTPCR0: %08X", SH7305_POWER.MSTPCR0.lword);
        dprint(8, 210, C_BLACK, "MSTPCR2: %08X", SH7305_POWER.MSTPCR2.lword);

        dprint(8, 250, C_BLACK, "FSICLKCR: %08X", SH7305_CPG.FSICLKCR.lword);
        dprint(8, 270, C_BLACK, "SPUCLKCR: %08X", SH7305_CPG.SPUCLKCR.lword);

        volatile uint32_t *ccr = (void *)0xff00001c;
        dprint(8, 310, C_BLACK, "CCR: %08X", *ccr);

        dupdate();

        if(getkey().key == KEY_EXIT) {
            return 1;
        }
    }
}

Notes

The gint/mpu headers expose mapped hardware registers as C structures. This is cleaner than manually hardcoding every address.

Only write to hardware registers when you know what the register does. A wrong write can freeze the calculator.