Sansa AMS: Time has shown that switching between 16 and 32bit mode costs much time (due to the micro delay needed), so do 32bit transfers unconditionally for lcd updates at the cost of updating slightly larger rectangles (gives upto 15% speed up, nearly at maximum now).

Unify this optimized dbop transfer function and re-use it more often (it still handles 16bit transfers).

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@24198 a1c6a512-1295-4272-9138-f99709370657

firmware/target/arm/as3525/dbop-as3525.c

@@ -20,6 +20,7 @@
  ****************************************************************************/
 
 #include "config.h"
+#include <inttypes.h>
 #include "as3525.h"
 #include "dbop-as3525.h"
 
@@ -75,3 +76,50 @@ unsigned short dbop_debug(void)
 {
     return dbop_input_value;
 }
+
+static inline void dbop_set_mode(int mode)
+{
+    int delay = 10;
+    if (mode == 32 && (!(DBOP_CTRL & (1<<13|1<<14))))
+        DBOP_CTRL |= (1<<13|1<<14);
+    else if (mode == 16 && (DBOP_CTRL & (1<<13|1<<14)))
+        DBOP_CTRL &= ~(1<<14|1<<13);
+    else
+        return;
+    while(delay--) asm volatile("nop");
+}
+
+void dbop_write_data(const int16_t* p_bytes, int count)
+{
+    
+    const int32_t *data;
+    if ((intptr_t)p_bytes & 0x3 || count == 1)
+    {   /* need to do a single 16bit write beforehand if the address is
+         * not word aligned or count is 1, switch to 16bit mode if needed */
+        dbop_set_mode(16);
+        DBOP_DOUT16 = *p_bytes++;
+        if (!(--count))
+            return;
+    }
+    /* from here, 32bit transfers are save
+     * set it to transfer 4*(outputwidth) units at a time,
+     * if bit 12 is set it only does 2 halfwords though (we never set it)
+     * switch to 32bit output if needed */
+    dbop_set_mode(32);
+    data = (int32_t*)p_bytes;
+    while (count > 1)
+    {
+        DBOP_DOUT32 = *data++;
+        count -= 2;
+
+        /* Wait if push fifo is full */
+        while ((DBOP_STAT & (1<<6)) != 0);
+    }
+    /* While push fifo is not empty */
+    while ((DBOP_STAT & (1<<10)) == 0);
+
+    /* due to the 32bit alignment requirement or uneven count,
+     * we possibly need to do a 16bit transfer at the end also */
+    if (count > 0)
+        dbop_write_data((int16_t*)data, 1);
+}