/*
 * bank_io — HOME-resident helpers to read/write a "far" page that lives
 * in some physical RAM page outside the currently-mapped W3 bank.
 *
 *   - We always run from HOME (window 1, always mapped), so we are free
 *     to swap W3 (port 0xE2) between the caller's bank and the data
 *     page, then restore it before returning.
 *   - The caller must not rely on W3 contents during the call — the swap
 *     is transparent to instruction-fetch (we execute from W1), and only
 *     this function touches W3.
 *   - DI/EI is NOT applied around the swap; ISRs in HOME are unaffected,
 *     and banked-call ISRs are not expected in our current design.
 */

#include <stdint.h>
#include <string.h>
#include <sprinter.h>
#include <sprinter_mem.h>

uint8_t bank_load_byte(uint8_t phys_page, uint16_t off_in_window)
{
    uint8_t saved = _io_page_w3;
    sprinter_page_w3(phys_page);
    uint8_t v = *((volatile uint8_t *)(0xC000u + off_in_window));
    sprinter_page_w3(saved);
    return v;
}

void bank_store_byte(uint8_t phys_page, uint16_t off_in_window, uint8_t v)
{
    uint8_t saved = _io_page_w3;
    sprinter_page_w3(phys_page);
    *((volatile uint8_t *)(0xC000u + off_in_window)) = v;
    sprinter_page_w3(saved);
}

void bank_read(uint8_t phys_page, uint16_t off, void *dst, uint16_t n)
{
    uint8_t saved = _io_page_w3;
    sprinter_page_w3(phys_page);
    memcpy(dst, (const void *)(0xC000u + off), n);
    sprinter_page_w3(saved);
}

void bank_write(uint8_t phys_page, uint16_t off, const void *src, uint16_t n)
{
    uint8_t saved = _io_page_w3;
    sprinter_page_w3(phys_page);
    memcpy((void *)(0xC000u + off), src, n);
    sprinter_page_w3(saved);
}