From ecf7dae267b27a705009528ea18113235d674f65 Mon Sep 17 00:00:00 2001
From: Vegard Storheil Eriksen <zyp@jvnv.net>
Date: Sat, 22 Sep 2012 15:47:10 +0200
Subject: Output received audio data over I2S.

---
 laks     |  2 +-
 main.cpp | 64 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-----
 2 files changed, 60 insertions(+), 6 deletions(-)

diff --git a/laks b/laks
index 95729b7..0ca572b 160000
--- a/laks
+++ b/laks
@@ -1 +1 @@
-Subproject commit 95729b7fd4de6704823ab8033593abe352134916
+Subproject commit 0ca572bc7a0fbe26b216cab519d89187ae49a28b
diff --git a/main.cpp b/main.cpp
index 4c3b661..4b36241 100644
--- a/main.cpp
+++ b/main.cpp
@@ -3,6 +3,21 @@
 #include <os/time.h>
 #include <usb/usb.h>
 #include <usb/descriptor.h>
+#include <spi/spi.h>
+#include <dma/dma.h>
+
+Pin& i2s_mck = PC7;
+Pin& i2s_sck = PC10;
+Pin& i2s_sd  = PC12;
+Pin& i2s_ws  = PA4;
+
+Pin& usb_vbus = PA9;
+Pin& usb_dm   = PA11;
+Pin& usb_dp   = PA12;
+
+const uint32_t audio_buf_size = 256;
+uint16_t audio_buf[audio_buf_size];
+uint32_t audio_buf_pos = 0;
 
 struct AS_General_desc {
 	uint8_t bLength;
@@ -64,10 +79,6 @@ auto conf_desc = configuration_desc(2, 1, 0, 0xc0, 0,
 desc_t dev_desc_p = {sizeof(dev_desc), (void*)&dev_desc};
 desc_t conf_desc_p = {sizeof(conf_desc), (void*)&conf_desc};
 
-Pin& usb_vbus = PA9;
-Pin& usb_dm   = PA11;
-Pin& usb_dp   = PA12;
-
 USB_otg usb(OTG_FS, dev_desc_p, conf_desc_p);
 
 class USB_Audio : public USB_class_driver {
@@ -129,20 +140,63 @@ class USB_Audio : public USB_class_driver {
 				
 			} else if(ep == 1) {
 				usb_rblog.log("Received audio frame with %d bytes.", len);
-				//uint32_t r_len = usb.read(ep, buf, len);
+				
+				if(audio_buf_pos + (len >> 1) >= audio_buf_size) {
+					usb.read(1, (uint32_t*)&audio_buf[audio_buf_pos], (audio_buf_size - audio_buf_pos) << 1);
+					len -= (audio_buf_size - audio_buf_pos) << 1;
+					audio_buf_pos = 0;
+				}
+				
+				if(len) {
+					usb.read(1, (uint32_t*)&audio_buf[audio_buf_pos], len);
+					audio_buf_pos += len >> 1;
+				}
 			}
 		}
 };
 
 USB_Audio usb_audio(usb);
 
+
 int main() {
 	// Initialize system timer.
 	STK.LOAD = 168000000 / 8 / 1000; // 1000 Hz.
 	STK.CTRL = 0x03;
 	
 	RCC.enable(RCC.GPIOA);
+	RCC.enable(RCC.GPIOB);
+	RCC.enable(RCC.GPIOC);
+	
+	// Initialize I2S.
+	i2s_mck.set_mode(Pin::AF);
+	i2s_mck.set_af(6);
+	i2s_sck.set_mode(Pin::AF);
+	i2s_sck.set_af(6);
+	i2s_sd.set_mode(Pin::AF);
+	i2s_sd.set_af(6);
+	i2s_ws.set_mode(Pin::AF);
+	i2s_ws.set_af(6);
+	
+	RCC.PLLI2SCFGR = (3 << 28) | (258 << 6);
+	RCC.CR |= 1 << 26;
+	while(!(RCC.CR & (1 << 27)));
+	
+	RCC.enable(RCC.SPI3);
+	
+	SPI3.reg.I2SPR = 0x303;
+	SPI3.reg.I2SCFGR = 0xe00;
+	SPI3.reg.CR2 = 2;
+	
+	// Initialize DMA.
+	RCC.enable(RCC.DMA1);
+	
+	DMA1.reg.S[7].CR = (0 << 25) | (1 << 13) | (1 << 11) | (1 << 10) | (1 << 8) | (1 << 6);
+	DMA1.reg.S[7].PAR = uint32_t(&SPI3.reg.DR);
+	DMA1.reg.S[7].M0AR = uint32_t(&audio_buf);
+	DMA1.reg.S[7].NDTR = audio_buf_size;
+	DMA1.reg.S[7].CR |= 1;
 	
+	// Initialize USB.
 	usb_vbus.set_mode(Pin::Input);
 	usb_dm.set_mode(Pin::AF);
 	usb_dm.set_af(10);
-- 
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