From: Keith Packard <keithp@keithp.com>
Date: Thu, 2 Nov 2017 16:10:54 +0000 (-0700)
Subject: altos: Add vblank signal to vga driver
X-Git-Url: https://git.gag.com/?p=fw%2Faltos;a=commitdiff_plain;h=2418a1297af8f43e338067321779328c59b4a96c

altos: Add vblank signal to vga driver

Allow applications to sync with vblank.

Signed-off-by: Keith Packard <keithp@keithp.com>
---

diff --git a/src/drivers/ao_vga.c b/src/drivers/ao_vga.c
index 909e3109..59658caf 100644
--- a/src/drivers/ao_vga.c
+++ b/src/drivers/ao_vga.c
@@ -91,6 +91,8 @@ static uint32_t	*scanline;
 			 (en << STM_DMA_CCR_EN))
 
 
+uint8_t	ao_vga_vblank;
+
 void stm_tim2_isr(void)
 {
 	int16_t	line = stm_tim3.cnt;
@@ -111,6 +113,10 @@ void stm_tim2_isr(void)
 		if (((line - VBLANK_END) & 1))
 			scanline += AO_VGA_STRIDE;
 	} else {
+		if (line == VBLANK_START) {
+			ao_vga_vblank = 1;
+			ao_wakeup(&ao_vga_vblank);
+		}
 		scanline = ao_vga_fb;
 	}
 	stm_tim2.sr = 0;
diff --git a/src/drivers/ao_vga.h b/src/drivers/ao_vga.h
index 7d9d6b39..92cdb76c 100644
--- a/src/drivers/ao_vga.h
+++ b/src/drivers/ao_vga.h
@@ -36,4 +36,6 @@ extern uint32_t	ao_vga_fb[AO_VGA_STRIDE * AO_VGA_HEIGHT];
 
 extern const struct ao_bitmap ao_vga_bitmap;
 
+extern uint8_t	ao_vga_vblank;
+
 #endif /* _AO_VGA_H_ */