FLASH_DUKR = 0xAE;
FLASH_DUKR = 0x56;

@eeprom e1;

e1 = 0x5A

/**
* @file  flash.c
* @brief Flash memory driver
*
* Implements 2 functions: block erase and block write. Block size is 64 bytes.
* This is done to minimize EEPROM programming time.
* Since programming code must be executed from RAM, the machine code is in the
* form of static arrays with corresponding assembly and C code shown in
* comments.
*/

#include "flash.h"
#include "stm8regs.h"

/*
void
block_erase(uint8_t *dst)
{
        FLASH_CR2 = 0x20;
        FLASH_NCR2 = 0xDF;
        *dst++ = 0;
        *dst++ = 0;
        *dst++ = 0;
        *dst = 0;
}
*/

static uint8_t block_erase_code[] = {
        0x35, 0x20, 0x50, 0x5B, /* MOV FLASH_CR2, #0x20  */
        0x35, 0xDF, 0x50, 0x5C, /* MOV FLASH_NCR2, #0xDF */
        0x4F,                   /* CLR A                 */
        0xF7,                   /* LD (X), A             */
        0x5C,                   /* INCW X                */
        0xF7,                   /* LD (X), A             */
        0x5C,                   /* INCW X                */
        0xF7,                   /* LD (X), A             */
        0x5C,                   /* INCW X                */
        0xF7,                   /* LD (X), A             */
        0x81,                   /* RET                   */
};

static void (*const block_erase)(uint8_t *dst) = (void (*)(uint8_t *dst))block_erase_code;

/*
void
block_write(uint8_t *src, uint8_t *dst)
{
        int8_t i;
        FLASH_CR2 = 0x10;
        FLASH_NCR2 = 0xEF;
        for (i = 64; i > 0; i--)
        {
                *dst++ = *src++;
        }
}
*/

static uint8_t block_write_code[] = {
        0x35, 0x10, 0x50, 0x5B, /* MOV FLASH_CR2, #0x10  */
        0x35, 0xEF, 0x50, 0x5C, /* MOV FLASH_NCR2, #0xDF */
        0x35, 0x40, 0x00, 0x00, /* MOV ?b0, #0x40        */
        0xF6,             /* loop: LD A, (X)             */
        0x90, 0xF7,             /* LD (Y), A             */
        0x5C,                   /* INCW X                */
        0x90, 0x5C,             /* INCW Y                */
        0xB6, 0x00,             /* LD A, ?b0             */
        0x4A,                   /* DEC A                 */
        0xB7, 0x00,             /* LD ?b0, A             */
        0x26, 0xF3,             /* JRNE loop             */
        0x81,                   /* RET                   */
};

static void (*const block_write)(uint8_t *src, uint8_t *dst) = (void (*)(uint8_t *src, uint8_t *dst))block_write_code;

static uint8_t block_buffer[64];

/**
* Unlock data EEPROM
*/
void
flash_init(void)
{
        FLASH_DUCR = 0xAE;
        FLASH_DUCR = 0x56;
}

/**
* Get a pointer to block buffer.
* Fill this buffer prior to calling flash_writeblock().
*/
void*
flash_getbuffer(void)
{
        return block_buffer;
}

/**
* Erase a 64-byte block
*/
void
flash_eraseblock(void* addr)
{
        block_erase(addr);
}

/**
* Write the contents of block_buffer into a 64-byte block
*/
void
flash_writeblock(void* addr)
{
        block_write(block_buffer, addr);
}