FS#10756 - Free unused init code

Introduce a new .init section for initialisation code, so that it can be copied to an area which is later overwritten before calling. The stack/bss can then overwrite that code, effectively freeing the code size that the initialisation routines need. Gives a few kB ram usage back.
Only implemented for PP and as3525 so far. More targets could be added, as well as more functions.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@25013 a1c6a512-1295-4272-9138-f99709370657

4 files changed, 58 insertions, 6 deletions

diff --git a/firmware/target/arm/as3525/app.lds b/firmware/target/arm/as3525/app.lds
index eb5b28f852..6e610d6e15 100644
--- a/firmware/target/arm/as3525/app.lds
+++ b/firmware/target/arm/as3525/app.lds
@@ -99,6 +99,8 @@ SECTIONS
         _iramend = .;
     } > IRAM AT> DRAM
 
+    _iramcopy = LOADADDR(.iram);
+
     .ibss (NOLOAD) :
     {
         _iedata = .;
@@ -108,9 +110,17 @@ SECTIONS
         _iend = .;
     } > IRAM
 
-    _iramcopy = LOADADDR(.iram);
+    .init ENDAUDIOADDR : 
+    {
+        . = ALIGN(4);
+        _initstart = .;
+        *(.init)
+        _initend = .;
+    } AT> DRAM
+
+    _initcopy = LOADADDR(.init);
 
-    .stack (NOLOAD) :
+    .stack _iramcopy (NOLOAD) :
     {
        *(.stack)
        stackbegin = .;
diff --git a/firmware/target/arm/crt0-pp.S b/firmware/target/arm/crt0-pp.S
index 9c996960cc..4e16df0f7a 100644
--- a/firmware/target/arm/crt0-pp.S
+++ b/firmware/target/arm/crt0-pp.S
@@ -213,6 +213,19 @@ cpu_init:
     strhi  r5, [r3], #4
     bhi    1b
 
+#ifdef INIT_ATTR
+    /* copy init code to codec buffer */
+    ldr    r2, =_initstart
+    ldr    r3, =_initend
+    ldr    r4, =_initcopy
+
+1:
+    cmp     r3, r2
+    ldrhi   r5, [r4], #4
+    strhi   r5, [r2], #4
+    bhi 1b
+#endif
+
     /* Zero out IBSS */
     ldr    r2, =_iedata
     ldr    r3, =_iend
diff --git a/firmware/target/arm/crt0.S b/firmware/target/arm/crt0.S
index 238cfdd65a..6284bcb16c 100644
--- a/firmware/target/arm/crt0.S
+++ b/firmware/target/arm/crt0.S
@@ -71,6 +71,7 @@ newstart:
     bhi     1b
 
     /* Copy the IRAM */
+    /* must be done before bss is zeroed */
     ldr     r2, =_iramcopy
     ldr     r3, =_iramstart
     ldr     r4, =_iramend
@@ -79,6 +80,23 @@ newstart:
     ldrhi   r5, [r2], #4
     strhi   r5, [r3], #4
     bhi     1b
+
+#endif
+
+#ifdef INIT_ATTR
+    /* copy init data to codec buffer */
+    /* must be done before bss is zeroed */
+    ldr    r2, =_initcopy
+    ldr    r3, =_initstart
+    ldr    r4, =_initend
+1:
+    cmp     r4, r3
+    ldrhi   r5, [r2], #4
+    strhi   r5, [r3], #4
+    bhi     1b
+
+    mov     r2, #0
+    mcr     p15, 0, r2, c7, c5, 0   @ Invalidate ICache
 #endif
 
     /* Initialise bss section to zero */
@@ -89,7 +107,7 @@ newstart:
     cmp     r3, r2
     strhi   r4, [r2], #4
     bhi     1b
-    
+
     /* Set up some stack and munge it with 0xdeadbeef */
     ldr     sp, =stackend
     ldr     r2, =stackbegin
@@ -115,7 +133,6 @@ newstart:
 
     /* Switch back to supervisor mode */
     msr     cpsr_c, #0xd3
-
     bl      main
 
 
diff --git a/firmware/target/arm/sandisk/app.lds b/firmware/target/arm/sandisk/app.lds
index 3010644b72..ec26fdbe38 100644
--- a/firmware/target/arm/sandisk/app.lds
+++ b/firmware/target/arm/sandisk/app.lds
@@ -37,8 +37,8 @@ STARTUP(target/arm/crt0-pp.o)
 
 MEMORY
 {
-    DRAM : ORIGIN = DRAMORIG, LENGTH = DRAMSIZE
-    IRAM : ORIGIN = IRAMORIG, LENGTH = IRAMSIZE
+    DRAM : ORIGIN = DRAMORIG,     LENGTH = DRAMSIZE
+    IRAM : ORIGIN = IRAMORIG,     LENGTH = IRAMSIZE
 }
 
 SECTIONS
@@ -126,6 +126,17 @@ SECTIONS
 
     _iramcopy = LOADADDR(.iram);
 
+
+    .init ENDAUDIOADDR : 
+    {
+        . = ALIGN(4);
+        _initstart = .;
+        *(.init)
+        _initend = .;
+    } AT> DRAM
+
+    _initcopy = LOADADDR(.init);
+
     .idle_stacks (NOLOAD) :
     {
        *(.idle_stacks)
@@ -175,6 +186,7 @@ SECTIONS
     .audiobuf (NOLOAD) :
     {
         _audiobuffer = .;
+        . = ALIGN(0x4);
         audiobuffer = .;
     } > DRAM