Subversion Repositories openrisc_me

; crt0.s - Startup code for the mrisc1. This code initializes the C
;              run-time model.
;
;
; Copyright 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
;
;  The authors hereby grant permission to use, copy, modify, distribute,
;  and license this software and its documentation for any purpose, provided
;  that existing copyright notices are retained in all copies and that this
;  notice is included verbatim in any distributions. No written agreement,
;  license, or royalty fee is required for any of the authorized uses.
;  Modifications to this software may be copyrighted by their authors
;  and need not follow the licensing terms described here, provided that
;  the new terms are clearly indicated on the first page of each file where
;  they apply.
;

        ; Create a label for the start of the eh_frame section.
        .section .eh_frame
__eh_frame_begin:

        .text
        .global _start
_start:
        ;; Initialize the stack pointer
        ldui    sp, #%hi16(__stack)
        addui   sp, sp, #%lo16(__stack)
        or      fp, sp, sp
        ;; Zero the bss space
        ldui    r9, #%hi16(__bss_start)
        addui   r9, r9, #%lo16(__bss_start)
        ldui    r10, #%hi16(__bss_end)
        addui   r10, r10, #%lo16(__bss_end)
        or      r0, r0, r0
        brle    r10, r9, .Lnext1
        or      r0, r0, r0
.Lcpy0: 
        stw     r0, r9, #0
        addi    r9, r9, #4
        or      r0, r0, r0      ; nop
        brle    r9, r10, .Lcpy0
        or      r0, r0, r0      ; nop

.Lnext1:
        ;; Copy data from ROM to Frame Buffer (on-chip memory)
        ldui    r9, #%hi16(_fbdata_start)
        ori     r9, r9, #%lo16(_fbdata_start)
        ldui    r10, #%hi16(_fbdata_end)
        ori     r10, r10, #%lo16(_fbdata_end)
        ldui    r11, #%hi16(_fbdata_vma)
        brle    r10, r9, .Lnext2
        ori     r11, r11, #%lo16(_fbdata_vma)
.Lcpy1:
        ldw     r5, r9, #$0
        addi    r9, r9, #$4
        stw     r5, r11, #$0
        brlt    r9, r10, .Lcpy1
        addi    r11, r11, #$4

.Lnext2:
        ;; Zero the frame buffer bss section
        ldui    r9, #%hi16(_fbbss_start)
        ori     r9, r9, #%lo16(_fbbss_start)
        ldui    r10, #%hi16(_fbbss_end)
        ori     r10, r10, #%lo16(_fbbss_end)
        or      r0, r0, r0
        brle    r10, r9, .Lnext3
        or      r0, r0, r0
.Lcpy2:
        stw     r0, r9, #$0
        addi    r9, r9, #$4
        or      r0, r0, r0
        brle    r9, r10, .Lcpy2
        or      r0, r0, r0

.Lnext3:
        ;; Call global and static constructors
        ldui    r10, #%hi16(_init)
        ori     r10, r10, #%lo16(_init)
        or      r0, r0, r0      ; nop
        jal     r14, r10
        or      r0, r0, r0      ; nop

        ;; Call main
        ldui    r10, #%hi16(main)
        ori     r10, r10, #%lo16(main)
        or      r0, r0, r0      ; nop
        jal     r14, r10
        or      r0, r0, r0      ; nop

        ;; DJK - Added 12Nov01. Pass main's return value to exit.
        or      r1, r11, r0

        ;; Jump to exit
        ldui    r10, #%hi16(exit)
        ori     r10, r10, #%lo16(exit)
        or      r0, r0, r0      ; nop
        jal     r14, r10
        or      r0, r0, r0      ; nop

        ;; Exit does not return, however, this code is to catch an
        ;;   error if it does. Set the processor into sleep mode.
        ori     r1, r0, #$1
        stw     r1, r0, #%lo16(_DEBUG_HALT_REG)
        or      r0, r0, r0
        or      r0, r0, r0
        or      r0, r0, r0
        or      r0, r0, r0
        or      r0, r0, r0
.Lend:
        jmp .Lend
        or      r0, r0, r0