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; 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