Added double buffering (untested)

1 files changed, 14 insertions, 6 deletions

diff --git a/firmware/main.c b/firmware/main.c
index 89473de..32b9c31 100644
--- a/firmware/main.c
+++ b/firmware/main.c
@@ -67,7 +67,10 @@ unsigned const char const CRATE_MAP[CRATES_PER_BUS] = {
 #define SYSTICKS_PER_SECOND		100

 #define SYSTICK_PERIOD_MS		(1000 / SYSTICKS_PER_SECOND)

 

-unsigned char framebuffer[BUS_COUNT*BUS_SIZE];

+unsigned char framebuffer1[BUS_COUNT*BUS_SIZE];

+unsigned char framebuffer2[BUS_COUNT*BUS_SIZE];

+unsigned char *framebuffer_input = framebuffer1;

+unsigned char *framebuffer_output = framebuffer2;

 unsigned long framebuffer_read(void *data, unsigned long len);

 /* Kick off DMA transfer from RAM to SPI interfaces */

 void kickoff_transfers(void);

@@ -167,10 +170,10 @@ unsigned long framebuffer_read(void *data, unsigned long len) {
 			unsigned int bottle	= BOTTLE_MAP[x + y*CRATE_WIDTH];

 			unsigned int dst	= bus*BUS_SIZE + (crate*CRATE_SIZE + bottle)*3;

 			unsigned int src	= (y*CRATE_WIDTH + x)*3;

-			// Copy r, g and b data

-			framebuffer[dst]	 = fb->rgb_data[src];

-			framebuffer[dst + 1] = fb->rgb_data[src + 1];

-			framebuffer[dst + 2] = fb->rgb_data[src + 2];

+			/* Copy r, g and b data */

+			framebuffer_input[dst]	 = fb->rgb_data[src];

+			framebuffer_input[dst + 1] = fb->rgb_data[src + 1];

+			framebuffer_input[dst + 2] = fb->rgb_data[src + 2];

 		}

 	}

 

@@ -180,6 +183,11 @@ unsigned long framebuffer_read(void *data, unsigned long len) {
 }

 

 void kickoff_transfers() {

+	/* Swap buffers */

+	unsigned char *tmp = framebuffer_output;

+	framebuffer_output = framebuffer_input;

+	framebuffer_input = tmp;

+	/* Re-schedule DMA transfers */

 	kickoff_transfer(11, 0, SSI0_BASE);

 	kickoff_transfer(25, 1, SSI1_BASE);

 	kickoff_transfer(13, 2, SSI2_BASE);

@@ -187,7 +195,7 @@ void kickoff_transfers() {
 }

 

 void kickoff_transfer(unsigned int channel, unsigned int offset, int base) {

-	ROM_uDMAChannelTransferSet(channel | UDMA_PRI_SELECT, UDMA_MODE_BASIC, framebuffer+BUS_SIZE*offset, (void *)(base + SSI_O_DR), BUS_SIZE);

+	ROM_uDMAChannelTransferSet(channel | UDMA_PRI_SELECT, UDMA_MODE_BASIC, framebuffer_output+BUS_SIZE*offset, (void *)(base + SSI_O_DR), BUS_SIZE);

 	ROM_uDMAChannelEnable(channel);

 }