--- /dev/null
+// crt1-tiny.S
+//
+// This is a reduced version of the code in crt1-boards.S .
+// For most hardware / boards, this code sets up the C calling context
+// (setting up stack, PS, and clearing BSS) and calls main().
+// It has some limitations (see LSP Ref Manual for details) such as:
+// - does not setup the C library (...)
+// - does not call C++ static constructors and destructors
+// - only clears .bss , not other *.bss sections
+//
+// Control arrives here at _start from the reset vector or from crt0-app.S.
+
+// Copyright (c) 1998-2010 Tensilica Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining
+// a copy of this software and associated documentation files (the
+// "Software"), to deal in the Software without restriction, including
+// without limitation the rights to use, copy, modify, merge, publish,
+// distribute, sublicense, and/or sell copies of the Software, and to
+// permit persons to whom the Software is furnished to do so, subject to
+// the following conditions:
+//
+// The above copyright notice and this permission notice shall be included
+// in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+// IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+// CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+// TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+// SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+#include <xtensa/coreasm.h>
+
+
+// Imports
+// __stack from linker script (see LSP Ref Manual)
+// _bss_start from linker script (see LSP Ref Manual)
+// _bss_end from linker script (see LSP Ref Manual)
+// main from user application
+
+
+
+#ifdef __XTENSA_CALL0_ABI__
+# define CALL call0
+#else
+# define CALL call4
+#endif
+
+
+/**************************************************************************/
+
+ .text
+ .global _start
+_start:
+ // _start is typically NOT at the beginning of the text segment --
+ // it is always called from either the reset vector or other code
+ // that does equivalent initialization (such as crt0-app.S).
+ // See crt1-boards.S for assumptions on entry to _start ,
+ // and for comments on what is being done in this file.
+
+#if !XCHAL_HAVE_HALT || !XCHAL_HAVE_BOOTLOADER // not needed for Xtensa TX
+ movi a0, 0 // mark base of call stack
+#endif
+
+ movi sp, __stack // setup the stack
+
+#if XCHAL_HAVE_EXCEPTIONS
+# ifdef __XTENSA_CALL0_ABI__
+ movi a3, PS_UM // PS: WOE=0, UM=1, EXCM=0, INTLEVEL=0
+# else
+ movi a3, PS_UM|PS_WOE // PS: WOE=1, UM=1, EXCM=0, INTLEVEL=0
+# endif
+ wsr a3, PS // setup PS for the application
+ rsync
+#endif
+
+
+ // Clear the BSS (uninitialized data) segment.
+ //
+ // This code only supports .bss, not multiple *.bss sections.
+ // Corresponding code in crt1-boards.S does, and is faster but bigger.
+
+#if !XCHAL_HAVE_BOOTLOADER
+ movi a6, _bss_start
+ movi a7, _bss_end
+ bgeu a6, a7, 2f
+1: s32i a0, a6, 0
+ addi a6, a6, 4
+ bltu a6, a7, 1b
+2:
+#endif
+
+ // We can now call C code, the C calling environment is initialized.
+ // This tiny C runtime assumes main is declared as "void main(void)"
+ // rather than with the usual argc,argv. So there are no arguments.
+
+ CALL main
+
+ // In this tiny C runtime, main() is not expected to return.
+ // If it does, just loop forever.
+
+ //CALL xthal_dcache_all_writeback // sync dirty dcaches to memory
+ //extw // sync TIE queues/ports/etc (LX or later only)
+
+.L0:
+#if XCHAL_HAVE_DEBUG
+ break 1, 15 // give control to debugger
+#elif XCHAL_HAVE_HALT
+ halt
+#endif
+ j .L0
+
+ .size _start, . - _start
+
+
+// Local Variables:
+// mode:fundamental
+// comment-start: "// "
+// comment-start-skip: "// *"
+// End:
projects / open-ath9k-htc-firmware.git / blobdiff