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cache pgm read data

This commit is contained in:
devsaurus 2015-02-10 22:04:43 +01:00
parent f2c881db18
commit 5fa0a0bc46
1 changed files with 17 additions and 4 deletions
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21
app/modules/u8g.c
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@ -25,15 +25,28 @@ static const u8g_fntpgm_uint8_t *font_array[] =
};
static uint32_t *u8g_pgm_cached_iadr = NULL;
static uint32_t u8g_pgm_cached_data;
// function to read 4-byte aligned from program memory AKA irom0
u8g_pgm_uint8_t u8g_pgm_read(const u8g_pgm_uint8_t *adr)
u8g_pgm_uint8_t ICACHE_FLASH_ATTR u8g_pgm_read(const u8g_pgm_uint8_t *adr)
{
uint32_t iadr = (uint32_t)adr;
// set up pointer to 4-byte aligned memory location
uint32_t *ptr = (uint32_t *)(iadr & ~0x3);
uint32_t pgm_data;
// read 4-byte aligned
uint32_t pgm_data = *ptr;
if (ptr == u8g_pgm_cached_iadr)
{
pgm_data = u8g_pgm_cached_data;
}
else
{
// read 4-byte aligned
pgm_data = *ptr;
u8g_pgm_cached_iadr = ptr;
u8g_pgm_cached_data = pgm_data;
}
// return the correct byte within the retrieved 32bit word
return pgm_data >> ((iadr % 4) * 8);
@ -962,7 +975,7 @@ const LUA_REG_TYPE lu8g_map[] =
{ LNILKEY, LNILVAL }
};
LUALIB_API int ICACHE_FLASH_ATTR luaopen_u8g( lua_State *L )
LUALIB_API int luaopen_u8g( lua_State *L )
{
#if LUA_OPTIMIZE_MEMORY > 0
luaL_rometatable(L, "u8g.display", (void *)lu8g_display_map); // create metatable