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Wait for vsync in lcd_blit calls #159

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Wait for vsync in lcd_blit calls #159

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18 changes: 18 additions & 0 deletions ndless/src/resources/syscalls.c
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Original file line number Diff line number Diff line change
Expand Up @@ -104,25 +104,39 @@ int sc_nl_exec(const char *prgm_path, int argsn, char *args[]) {
return ld_exec_with_args(prgm_path, argsn, args, NULL);
}

static void wait_for_vsync()
{
// Clear sync flag
*(volatile uint32_t*)(0xC0000028) = 0b100;
// Wait for sync flag set
while((*(volatile uint32_t*)(0xC0000020) & 0b100) == 0)
idle();
}

typedef void (*lcd_blit_func)(void *buffer);

static void lcd_blit_simple_565(void *buffer)
{
wait_for_vsync();
memcpy(REAL_SCREEN_BASE_ADDRESS, buffer, 320 * 240 * sizeof(uint16_t));
}

static void lcd_blit_simple_8(void *buffer)
{
wait_for_vsync();
memcpy(REAL_SCREEN_BASE_ADDRESS, buffer, 320 * 240 * sizeof(uint8_t));
}

static void lcd_blit_simple_4(void *buffer)
{
wait_for_vsync();
memcpy(REAL_SCREEN_BASE_ADDRESS, buffer, 320 * 240 / 2);
}

static void lcd_blit_320x240_240x320_8(void *buffer)
{
wait_for_vsync();

uint8_t *out = REAL_SCREEN_BASE_ADDRESS, *in = buffer;
for (int col = 0; col < 240; ++col)
{
Expand All @@ -134,6 +148,8 @@ static void lcd_blit_320x240_240x320_8(void *buffer)

static void lcd_blit_320x240_240x320_565(void *buffer)
{
wait_for_vsync();

uint16_t *out = REAL_SCREEN_BASE_ADDRESS, *in = buffer;
for (int col = 0; col < 240; ++col)
{
Expand All @@ -145,6 +161,8 @@ static void lcd_blit_320x240_240x320_565(void *buffer)

static void lcd_blit_240x320_320x240_565(void *buffer)
{
wait_for_vsync();

uint16_t *out = REAL_SCREEN_BASE_ADDRESS, *in = buffer;
for (int col = 0; col < 320; ++col)
{
Expand Down