circuitpython/extmod/machine_mem.c

// SPDX-FileCopyrightText: 2014 MicroPython & CircuitPython contributors (https://github.com/adafruit/circuitpython/graphs/contributors)
// SPDX-FileCopyrightText: Copyright (c) 2013, 2014 Damien P. George
//
// SPDX-License-Identifier: MIT

#include "py/runtime.h"
#include "extmod/machine_mem.h"

#if MICROPY_PY_MACHINE

// If you wish to override the functions for mapping the machine_mem read/write
// address, then add a #define for MICROPY_MACHINE_MEM_GET_READ_ADDR and/or
// MICROPY_MACHINE_MEM_GET_WRITE_ADDR in your mpconfigport.h. Since the
// prototypes are identical, it is allowable for both of the macros to evaluate
// the to same function.
//
// It is expected that the modmachine.c file for a given port will provide the
// implementations, if the default implementation isn't used.

#if !defined(MICROPY_MACHINE_MEM_GET_READ_ADDR) || !defined(MICROPY_MACHINE_MEM_GET_WRITE_ADDR)
STATIC uintptr_t machine_mem_get_addr(mp_obj_t addr_o, uint align) {
    uintptr_t addr = mp_obj_int_get_truncated(addr_o);
    if ((addr & (align - 1)) != 0) {
        mp_raise_ValueError_varg(translate("address %08x is not aligned to %d bytes"), addr, align);
    }
    return addr;
}
#if !defined(MICROPY_MACHINE_MEM_GET_READ_ADDR)
#define MICROPY_MACHINE_MEM_GET_READ_ADDR machine_mem_get_addr
#endif
#if !defined(MICROPY_MACHINE_MEM_GET_WRITE_ADDR)
#define MICROPY_MACHINE_MEM_GET_WRITE_ADDR machine_mem_get_addr
#endif
#endif

STATIC void machine_mem_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
    (void)kind;
    machine_mem_obj_t *self = MP_OBJ_TO_PTR(self_in);
    mp_printf(print, "<%u-bit memory>", 8 * self->elem_size);
}

STATIC mp_obj_t machine_mem_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value) {
    // TODO support slice index to read/write multiple values at once
    machine_mem_obj_t *self = MP_OBJ_TO_PTR(self_in);
    if (value == MP_OBJ_NULL) {
        // delete
        return MP_OBJ_NULL; // op not supported
    } else if (value == MP_OBJ_SENTINEL) {
        // load
        uintptr_t addr = MICROPY_MACHINE_MEM_GET_READ_ADDR(index, self->elem_size);
        uint32_t val;
        switch (self->elem_size) {
            case 1:
                val = (*(uint8_t *)addr);
                break;
            case 2:
                val = (*(uint16_t *)addr);
                break;
            default:
                val = (*(uint32_t *)addr);
                break;
        }
        return mp_obj_new_int(val);
    } else {
        // store
        uintptr_t addr = MICROPY_MACHINE_MEM_GET_WRITE_ADDR(index, self->elem_size);
        uint32_t val = mp_obj_get_int_truncated(value);
        switch (self->elem_size) {
            case 1:
                (*(uint8_t *)addr) = val;
                break;
            case 2:
                (*(uint16_t *)addr) = val;
                break;
            default:
                (*(uint32_t *)addr) = val;
                break;
        }
        return mp_const_none;
    }
}

const mp_obj_type_t machine_mem_type = {
    { &mp_type_type },
    .name = MP_QSTR_mem,
    .print = machine_mem_print,
    .subscr = machine_mem_subscr,
};

const machine_mem_obj_t machine_mem8_obj = {{&machine_mem_type}, 1};
const machine_mem_obj_t machine_mem16_obj = {{&machine_mem_type}, 2};
const machine_mem_obj_t machine_mem32_obj = {{&machine_mem_type}, 4};

#endif // MICROPY_PY_MACHINE