Jz4740:

 * Optimize & cleanup thread handling a bit
 * Unify exception return and fix a potential bug


git-svn-id: svn://svn.rockbox.org/rockbox/trunk@20659 a1c6a512-1295-4272-9138-f99709370657

1 files changed, 36 insertions, 39 deletions

diff --git a/firmware/thread.c b/firmware/thread.c
index 453fbf5..6efe825 100644
--- a/firmware/thread.c
+++ b/firmware/thread.c
@@ -937,23 +937,23 @@ static inline void core_sleep(void)
 void start_thread(void); /* Provide C access to ASM label */
 static void __attribute__((used)) _start_thread(void)
 {
-    /* $t1 = context */
+    /* t1 = context */
     asm volatile (
       "start_thread:          \n"
         ".set noreorder       \n"
         ".set noat            \n"
-        "lw     $8,    4($9)  \n" /* Fetch thread function pointer ($8 = $t0, $9 = $t1) */
+        "lw     $8,    4($9)  \n" /* Fetch thread function pointer ($8 = t0, $9 = t1) */
         "lw     $29,  40($9)  \n" /* Set initial sp(=$29) */
+        "jalr   $8            \n" /* Start the thread */
         "sw     $0,   48($9)  \n" /* Clear start address */
-        "jr     $8            \n" /* Start the thread */
-        "nop                  \n"
         ".set at              \n"
         ".set reorder         \n"
+        ::: "t0"
     );
     thread_exit();
 }
 
-/* Place context pointer in $s0 slot, function pointer in $s1 slot, and
+/* Place context pointer in s0 slot, function pointer in s1 slot, and
  * start_thread pointer in context_start */
 #define THREAD_STARTUP_INIT(core, thread, function)           \
     ({ (thread)->context.r[0] = (uint32_t)&(thread)->context, \
@@ -969,22 +969,21 @@ static inline void store_context(void* addr)
     asm volatile (
         ".set noreorder        \n"
         ".set noat             \n"
-        "move  $8, %0          \n"
-        "sw    $16,  0($8)     \n" /* $s0 */
-        "sw    $17,  4($8)     \n" /* $s1 */
-        "sw    $18,  8($8)     \n" /* $s2 */
-        "sw    $19, 12($8)     \n" /* $s3 */
-        "sw    $20, 16($8)     \n" /* $s4 */
-        "sw    $21, 20($8)     \n" /* $s5 */
-        "sw    $22, 24($8)     \n" /* $s6 */
-        "sw    $23, 28($8)     \n" /* $s7 */
-        "sw    $28, 32($8)     \n" /* gp */
-        "sw    $30, 36($8)     \n" /* fp */
-        "sw    $29, 40($8)     \n" /* sp */
-        "sw    $31, 44($8)     \n" /* ra */
+        "sw    $16,  0(%0)     \n" /* s0 */
+        "sw    $17,  4(%0)     \n" /* s1 */
+        "sw    $18,  8(%0)     \n" /* s2 */
+        "sw    $19, 12(%0)     \n" /* s3 */
+        "sw    $20, 16(%0)     \n" /* s4 */
+        "sw    $21, 20(%0)     \n" /* s5 */
+        "sw    $22, 24(%0)     \n" /* s6 */
+        "sw    $23, 28(%0)     \n" /* s7 */
+        "sw    $28, 32(%0)     \n" /* gp */
+        "sw    $30, 36(%0)     \n" /* fp */
+        "sw    $29, 40(%0)     \n" /* sp */
+        "sw    $31, 44(%0)     \n" /* ra */
         ".set at               \n"
         ".set reorder          \n"
-        : : "r" (addr) : "t0"
+        : : "r" (addr)
     );
 }
 
@@ -997,29 +996,27 @@ static inline void load_context(const void* addr)
     asm volatile (
         ".set noat             \n"
         ".set noreorder        \n"
-        "lw    $8, 48(%0)      \n" /* Get start address ($8 = $t0) */
+        "lw    $8, 48(%0)      \n" /* Get start address ($8 = t0) */
         "beqz  $8, running     \n" /* NULL -> already running */
         "nop                   \n"
-        "move  $9, %0          \n" /* $t1 = context */
         "jr    $8              \n"
-        "nop                   \n"
+        "move  $9, %0          \n" /* t1 = context */
     "running:                  \n"
-        "move  $8, %0          \n"
-        "lw    $16,  0($8)     \n" /* $s0 */
-        "lw    $17,  4($8)     \n" /* $s1 */
-        "lw    $18,  8($8)     \n" /* $s2 */
-        "lw    $19, 12($8)     \n" /* $s3 */
-        "lw    $20, 16($8)     \n" /* $s4 */
-        "lw    $21, 20($8)     \n" /* $s5 */
-        "lw    $22, 24($8)     \n" /* $s6 */
-        "lw    $23, 28($8)     \n" /* $s7 */
-        "lw    $28, 32($8)     \n" /* gp */
-        "lw    $30, 36($8)     \n" /* fp */
-        "lw    $29, 40($8)     \n" /* sp */
-        "lw    $31, 44($8)     \n" /* ra */
+        "lw    $16,  0(%0)     \n" /* s0 */
+        "lw    $17,  4(%0)     \n" /* s1 */
+        "lw    $18,  8(%0)     \n" /* s2 */
+        "lw    $19, 12(%0)     \n" /* s3 */
+        "lw    $20, 16(%0)     \n" /* s4 */
+        "lw    $21, 20(%0)     \n" /* s5 */
+        "lw    $22, 24(%0)     \n" /* s6 */
+        "lw    $23, 28(%0)     \n" /* s7 */
+        "lw    $28, 32(%0)     \n" /* gp */
+        "lw    $30, 36(%0)     \n" /* fp */
+        "lw    $29, 40(%0)     \n" /* sp */
+        "lw    $31, 44(%0)     \n" /* ra */
         ".set at               \n"
         ".set reorder          \n"
-        : : "r" (addr) : "t0" /* only! */
+        : : "r" (addr) : "t0", "t1"
     );
 }
 
@@ -1033,9 +1030,9 @@ static inline void core_sleep(void)
     __cpm_idle_mode();
 #endif
     asm volatile(".set   mips32r2           \n"
-                 "mfc0   $8, $12            \n" /* mfc $t0, $12 */
-                 "move   $9, $8             \n" /* move $t1, $t0 */
-                 "la     $10, 0x8000000     \n" /* la $t2, 0x8000000 */
+                 "mfc0   $8, $12            \n" /* mfc t0, $12 */
+                 "move   $9, $8             \n" /* move t1, t0 */
+                 "la     $10, 0x8000000     \n" /* la t2, 0x8000000 */
                  "or     $8, $8, $10        \n" /* Enable reduced power mode */
                  "mtc0   $8, $12            \n"
                  "wait                      \n"