From 9b596c80aacfc050c3533ca1c20493530d45b204 Mon Sep 17 00:00:00 2001
From: giomba <giomba@glgprograms.it>
Date: Sat, 15 Oct 2022 15:08:22 +0200
Subject: [PATCH] Pixels in sync with VSYNC and HSYNC.

---
 src/main.c  | 10 ++++++----
 src/vga.pio | 12 ++++++++----
 2 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/src/main.c b/src/main.c
index 0baa93e..8e5916b 100644
--- a/src/main.c
+++ b/src/main.c
@@ -22,7 +22,7 @@
 #define FRAMES 2
 
 #define HPIXEL 640
-#define VPIXEL 480
+#define VPIXEL 500
 #define BPP    1
 
 typedef struct Frame
@@ -93,11 +93,11 @@ int main()
 	// "draw" an horizontal dotted line (?)
 	for (unsigned int c = 0; c < 20; c += 3)
 	{
-		frames[0].data[80 * 64 + 20 + c] = 0x55;
+		frames[0].data[80 * 64 + 50 + c] = 0x55;
 	}
 	for (unsigned int c = 0; c < 20; c += 3)
 	{
-		frames[0].data[80 * 128 + 20 + c] = 0x99;
+		frames[0].data[80 * 128 + 50 + c] = 0x99;
 	}
 
 	// PIO and state machines
@@ -124,12 +124,14 @@ int main()
 	// low pulse assert lasts for 3 horizontal lines, then adjust by one
 	pio_sm_put_blocking(pio, sm2, 3 - 1);
 	pio_sm_put_blocking(pio, sm2, 500 - 3 - 1);
+	printf("OK\n");
 
 	// VGA pixel program
 	uint offset0 = pio_add_program(pio, &vga_free_run_program);
-	uint sm0 = pio_claim_unused_sm(pio, true);
+	uint sm0 = pio_claim_unused_sm(pio, false);
 	printf("Starting VGA pixel machine on %u...\n", sm0);
 	vga_pixel_program_init(pio, sm0, offset0);
+	pio_sm_put_blocking(pio, sm0, 640 - 1);
 
 	printf("Start!\n");
 
diff --git a/src/vga.pio b/src/vga.pio
index 12633b1..fc423eb 100644
--- a/src/vga.pio
+++ b/src/vga.pio
@@ -1,11 +1,15 @@
 .program vga_free_run
 
 entrypoint_vga_free_run:
+    pull
+    mov y, osr
+loope:
+    mov x, y
+    wait irq 0
 loop:
-    out pins, 1 [2]
-    nop
-    nop
-    jmp loop
+    out pins, 1
+    jmp x-- loop
+    jmp loope
 
 .program vga_hsync