From 71dc1a789ada01581e6a1be0f70c208e1eb2cddb Mon Sep 17 00:00:00 2001
From: Marcin Bukat <marcin.bukat@gmail.com>
Date: Tue, 12 Jun 2018 12:41:03 +0200
Subject: [PATCH] Fix MIPS threading code to compile with older compiler

Official rockbox mips gcc is old and doesn't support
symbolic register names in inline assembly

Change-Id: If67230d06e28ccf31b0f8f8e1b622275fed3f6ff
---
 firmware/asm/mips/thread-mips32.c | 68 +++++++++++++++----------------
 1 file changed, 34 insertions(+), 34 deletions(-)

diff --git a/firmware/asm/mips/thread-mips32.c b/firmware/asm/mips/thread-mips32.c
index 19efb6eea9..3e38685f1b 100644
--- a/firmware/asm/mips/thread-mips32.c
+++ b/firmware/asm/mips/thread-mips32.c
@@ -31,13 +31,13 @@ static void USED_ATTR start_thread(void *addr)
     asm volatile (
         ".set noreorder       \n"
         ".set noat            \n"
-        "lw     $t9,    4(%0)  \n" /* Fetch thread function pointer ($25 = t9) */
-        "lw     $sp,   40(%0)  \n" /* Set initial sp(=$29) */
-        "jalr   $t9            \n" /* Start the thread */
-        "sw     $zero, 48(%0)  \n" /* Clear start address */
+        "lw     $25,    4(%0) \n" /* Fetch thread function pointer ($25 = t9) */
+        "lw     $25,   40(%0) \n" /* Set initial sp(=$29) */
+        "jalr   $25           \n" /* Start the thread */
+        "sw     $0,    48(%0) \n" /* Clear start address */
         ".set at              \n"
         ".set reorder         \n"
-        : : "r" (addr) : "t9"
+        : : "r" (addr) : "$25"
     );
     thread_exit();
 }
@@ -59,18 +59,18 @@ static inline void store_context(void* addr)
     asm volatile (
         ".set noreorder        \n"
         ".set noat             \n"
-        "sw    $s0,  0(%0)     \n" /* s0 */
-        "sw    $s1,  4(%0)     \n" /* s1 */
-        "sw    $s2,  8(%0)     \n" /* s2 */
-        "sw    $s3, 12(%0)     \n" /* s3 */
-        "sw    $s4, 16(%0)     \n" /* s4 */
-        "sw    $s5, 20(%0)     \n" /* s5 */
-        "sw    $s6, 24(%0)     \n" /* s6 */
-        "sw    $s7, 28(%0)     \n" /* s7 */
-        "sw    $gp, 32(%0)     \n" /* gp */
-        "sw    $fp, 36(%0)     \n" /* fp */
-        "sw    $sp, 40(%0)     \n" /* sp */
-        "sw    $ra, 44(%0)     \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)
@@ -86,27 +86,27 @@ static inline void load_context(const void* addr)
     asm volatile (
         ".set noat             \n"
         ".set noreorder        \n"
-        "lw    $t9, 48(%0)     \n" /* Get start address ($8 = t0) */
-        "beqz  $t9, running    \n" /* NULL -> already running */
+        "lw    $25, 48(%0)     \n" /* Get start address (t9 = $25) */
+        "beqz  $25, running    \n" /* NULL -> already running */
         "nop                   \n"
-        "jr    $t9             \n"
-        "move  $a0, %0          \n" /* a0 = context branch delay slot anyway */
+        "jr    $25             \n"
+        "move  $4, %0          \n" /* a0 = context branch delay slot anyway */
     "running:                  \n"
-        "lw    $s0,  0(%0)     \n" /* s0 */
-        "lw    $s1,  4(%0)     \n" /* s1 */
-        "lw    $s2,  8(%0)     \n" /* s2 */
-        "lw    $s3, 12(%0)     \n" /* s3 */
-        "lw    $s4, 16(%0)     \n" /* s4 */
-        "lw    $s5, 20(%0)     \n" /* s5 */
-        "lw    $s6, 24(%0)     \n" /* s6 */
-        "lw    $s7, 28(%0)     \n" /* s7 */
-        "lw    $gp, 32(%0)     \n" /* gp */
-        "lw    $fp, 36(%0)     \n" /* fp */
-        "lw    $sp, 40(%0)     \n" /* sp */
-        "lw    $ra, 44(%0)     \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) : "t9"
+        : : "r" (addr) : "$25"
     );
 }