Subversion Repositories scarts

; crt0_2.s - Startup code for the mrisc1. This code initializes the C
;              run-time model.
;
; 12Nov01 (DJK) - The return code from main was not being passed to exit().
;                   Now it is passed as a parameter in R1.
;
; 10Sep01 (DJK) - The function exit() does not return. However, in the
;                   the case of device error (if the halt bit does not
;                   function properly, for instance), then a catch loop
;                   has been added.
;
;
; Copyright 2001, 2002, 2003, 2004 Morpho Technologies, Inc.
;

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

        .equ    HALT_REG, 0x300
        .section .text
        .global _start
_start:
        ;; Initialize the stack pointer
        ldui    sp, #%hi16(__stack)
        addui   sp, sp, #%lo16(__stack)
        or      fp, sp, sp

        ;; 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(__FRAME_BUFFER_START)
        brle    r10, r9, .Lnext1
        ori     r11, r11, #%lo16(__FRAME_BUFFER_START)
.Lcpy0:
        ldw     r5, r9, #$0
        addi    r9, r9, #$4
        stw     r5, r11, #$0
        brlt    r9, r10, .Lcpy0
        addi    r11, r11, #$4

.Lnext1:
        ;; Copy data from ROM to External Memory (off-chip memory)
        ldui    r9, #%hi16(_extdata_start)
        ori     r9, r9, #%lo16(_extdata_start)
        ldui    r10, #%hi16(_extdata_end)
        ori     r10, r10, #%lo16(_extdata_end)
        ldui    r11, #%hi16(__EXTERNAL_MEMORY_START)
        brle    r10, r9, .Lnext2
        ori     r11, r11, #%lo16(__EXTERNAL_MEMORY_START)
.Lcpy1:
        ldw     r5, r9, #$0
        addi    r9, r9, #$4
        stw     r5, r11, #$0
        brlt    r9, r10, .Lcpy1
        addi    r11, r11, #$4


.Lnext2:
        ;; 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, .Lnext3
        or      r0, r0, r0
.Lcpy2: 
        stw     r0, r9, #0
        addi    r9, r9, #4
        or      r0, r0, r0      ; nop
        brle    r9, r10, .Lcpy2
        or      r0, r0, r0      ; nop

.Lnext3:
        ;; Zero the external memory bss section
        ldui    r9, #%hi16(_extbss_start)
        ori     r9, r9, #%lo16(_extbss_start)
        ldui    r10, #%hi16(_extbss_end)
        ori     r10, r10, #%lo16(_extbss_end)
        or      r0, r0, r0
        brle    r10, r9, .Lnext4
        or      r0, r0, r0
.Lcpy3:
        stw     r0, r9, #$0
        addi    r9, r9, #$4
        or      r0, r0, r0
        brle    r9, r10, .Lcpy3
        or      r0, r0, r0

.Lnext4:
        ;; 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

        ;;  Setup destructors to be called from exit.
        ;;  (Just in case main never returns....)
        ldui    r10, #%hi16(atexit)
        ori     r10, r10, #%lo16(atexit)
        ldui    r1, #%hi16(_fini)
        ori     r1, r1, #%lo16(_fini)
        or      r0, r0, r0      ; nop
        jal     r14, r10
        or      r0, r0, r0      ; nop

        ;;  Initialise argc, argv and envp to empty
        addi    r1, r0, #0
        addi    r2, r0, #0
        addi    r3, r0, #0

        ;; 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, #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