diff --git a/core/include/esp/i2s_regs.h b/core/include/esp/i2s_regs.h
index 452299f..4414677 100644
--- a/core/include/esp/i2s_regs.h
+++ b/core/include/esp/i2s_regs.h
@@ -26,9 +26,11 @@ struct I2S_REGS {
     uint32_t volatile FIFO_CONF;        // 0x20
     uint32_t volatile RX_EOF_NUM;       // 0x24
     uint32_t volatile CONF_SINGLE_DATA; // 0x28
-    uint32_t volatile CONF_CHANNELS;     // 0x2c
+    uint32_t volatile CONF_CHANNELS;    // 0x2c
 };
 
+_Static_assert(sizeof(struct I2S_REGS) == 0x30, "I2S_REGS is the wrong size");
+
 /* Details for CONF register */
 
 #define I2S_CONF_BCK_DIV_M      0x0000003f
@@ -120,9 +122,9 @@ struct I2S_REGS {
 #define I2S_FIFO_CONF_TX_FIFO_MOD_M      0x00000007
 #define I2S_FIFO_CONF_TX_FIFO_MOD_S      13
 #define I2S_FIFO_CONF_DESCRIPTOR_ENABLE  BIT(12)
-#define I2S_FIFO_CONF_TX_DATA_NUM_M      0x0000003F
+#define I2S_FIFO_CONF_TX_DATA_NUM_M      0x0000003f
 #define I2S_FIFO_CONF_TX_DATA_NUM_S      6
-#define I2S_FIFO_CONF_RX_DATA_NUM_M      0x0000003F
+#define I2S_FIFO_CONF_RX_DATA_NUM_M      0x0000003f
 #define I2S_FIFO_CONF_RX_DATA_NUM_S      0
 
 /* Details for CONF_CHANNEL register */
diff --git a/core/include/esp/slc.h b/core/include/esp/slc.h
new file mode 100644
index 0000000..0322bad
--- /dev/null
+++ b/core/include/esp/slc.h
@@ -0,0 +1,37 @@
+/* esp/slc_regs.h
+ *
+ * ESP8266 SLC functions
+ */
+
+#ifndef _ESP_SLC_H
+#define _ESP_SLC_H
+
+#include "esp/slc_regs.h"
+
+/* Memory layout for DMA transfer descriptors. */
+
+struct SLCDescriptor
+{
+	uint32_t flags;
+	uint32_t buf_ptr;
+	uint32_t next_link_ptr;
+};
+
+#define SLC_DESCRIPTOR_FLAGS_BLOCKSIZE_M 0x00000fff
+#define SLC_DESCRIPTOR_FLAGS_BLOCKSIZE_S 0
+#define SLC_DESCRIPTOR_FLAGS_DATA_LENGTH_M 0x00000fff
+#define SLC_DESCRIPTOR_FLAGS_DATA_LENGTH_S 12
+#define SLC_DESCRIPTOR_FLAGS_SUB_SOF BIT(29)
+#define SLC_DESCRIPTOR_FLAGS_EOF BIT(30)
+#define SLC_DESCRIPTOR_FLAGS_OWNER BIT(31)
+
+#define SLC_DESCRIPTOR_FLAGS(blocksize,datalen,sub_sof,eof,owner) ( \
+	VAL2FIELD_M(SLC_DESCRIPTOR_FLAGS_BLOCKSIZE,blocksize)| \
+	VAL2FIELD_M(SLC_DESCRIPTOR_FLAGS_DATA_LENGTH,datalen)| \
+	((sub_sof)?SLC_DESCRIPTOR_FLAGS_SUB_SOF:0)| \
+	((eof)?SLC_DESCRIPTOR_FLAGS_EOF:0)| \
+	((owner)?SLC_DESCRIPTOR_FLAGS_OWNER:0) \
+) 
+
+
+#endif /* _ESP_SLC_REGS_H */
diff --git a/core/include/esp/slc_regs.h b/core/include/esp/slc_regs.h
index 5640e70..52d9a99 100644
--- a/core/include/esp/slc_regs.h
+++ b/core/include/esp/slc_regs.h
@@ -65,6 +65,8 @@ struct SLC_REGS {
     uint32_t volatile HOST_CONF_W5;            // 0xbc
 };
 
+_Static_assert(sizeof(struct SLC_REGS) == 0xc0, "SLC_REGS is the wrong size");
+
 /* Details for CONF0 register */
 
 #define SLC_CONF0_MODE_M                   0x00000003
@@ -269,7 +271,7 @@ struct SLC_REGS {
 #define SLC_SDIO_STATUS_BUS_M      0x00000007
 #define SLC_SDIO_STATUS_BUS_S      12
 #define SLC_SDIO_STATUS_WAKEUP     BIT(8)
-#define SLC_SDIO_STATUS_FUNC_M     0x0000000F
+#define SLC_SDIO_STATUS_FUNC_M     0x0000000f
 #define SLC_SDIO_STATUS_FUNC_S     4
 #define SLC_SDIO_STATUS_COMMAND_M  0x00000007
 #define SLC_SDIO_STATUS_COMMAND_S  0
@@ -284,28 +286,4 @@ struct SLC_REGS {
 #define SLC_RX_DESCRIPTOR_CONF_POP_IDLE_COUNT_M  0x0000ffff
 #define SLC_RX_DESCRIPTOR_CONF_POP_IDLE_COUNT_S  0
 
-struct SLCDescriptor
-{
-	uint32_t flags;
-	uint32_t buf_ptr;
-	uint32_t next_link_ptr;
-};
-
-#define SLC_DESCRIPTOR_FLAGS_BLOCKSIZE_M 0x00000fff
-#define SLC_DESCRIPTOR_FLAGS_BLOCKSIZE_S 0
-#define SLC_DESCRIPTOR_FLAGS_DATA_LENGTH_M 0x00000fff
-#define SLC_DESCRIPTOR_FLAGS_DATA_LENGTH_S 12
-#define SLC_DESCRIPTOR_FLAGS_SUB_SOF BIT(29)
-#define SLC_DESCRIPTOR_FLAGS_EOF BIT(30)
-#define SLC_DESCRIPTOR_FLAGS_OWNER BIT(31)
-
-#define SLC_DESCRIPTOR_FLAGS(blocksize,datalen,sub_sof,eof,owner) ( \
-	(((blocksize)&SLC_DESCRIPTOR_FLAGS_BLOCKSIZE_M)<<SLC_DESCRIPTOR_FLAGS_BLOCKSIZE_S)| \
-	(((datalen)&SLC_DESCRIPTOR_FLAGS_DATA_LENGTH_M)<<SLC_DESCRIPTOR_FLAGS_DATA_LENGTH_S)| \
-	((sub_sof)?SLC_DESCRIPTOR_FLAGS_SUB_SOF:0)| \
-	((eof)?SLC_DESCRIPTOR_FLAGS_EOF:0)| \
-	((owner)?SLC_DESCRIPTOR_FLAGS_OWNER:0) \
-) 
-
-
 #endif /* _ESP_SLC_REGS_H */