| 1 | ############################################################################## |
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| 2 | # crt0.s -- CR16 default start-up routine # |
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| 3 | # # |
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| 4 | # Copyright (c) 2004 National Semiconductor Corporation # |
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| 5 | # # |
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| 6 | # The authors hereby grant permission to use, copy, modify, distribute, # |
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| 7 | # and license this software and its documentation for any purpose, provided # |
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| 8 | # that existing copyright notices are retained in all copies and that this # |
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| 9 | # notice is included verbatim in any distributions. No written agreement, # |
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| 10 | # license, or royalty fee is required for any of the authorized uses. # |
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| 11 | # Modifications to this software may be copyrighted by their authors # |
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| 12 | # and need not follow the licensing terms described here, provided that # |
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| 13 | # the new terms are clearly indicated on the first page of each file where # |
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| 14 | # they apply. # |
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| 15 | # # |
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| 16 | # This is the start routine of your CR16 program. # |
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| 17 | # It is linked with your application automatically. You can use # |
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| 18 | # this routine as a template and modify it to your needs, yet this # |
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| 19 | # file must be supplied for the compiler. # |
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| 20 | # It is assumed that the following symbols are defined in your linker # |
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| 21 | # script: __STACK_START, __ISTACK_START # |
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| 22 | ############################################################################## |
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| 23 | |
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| 24 | .text |
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| 25 | #ifdef __CR16CP__ |
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| 26 | .align 4 |
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| 27 | #else |
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| 28 | .align 2 |
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| 29 | #endif |
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| 30 | .global _main |
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| 31 | .global _atexit |
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| 32 | .global _exit |
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| 33 | .global _start |
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| 34 | .global __fini |
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| 35 | .global __init |
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| 36 | .global __STACK_START |
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| 37 | .global __ISTACK_START |
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| 38 | |
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| 39 | _start: |
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| 40 | |
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| 41 | #----------------------------------------------------------------------------# |
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| 42 | # Initialize the stack pointers. The constants __STACK_START and # |
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| 43 | # __ISTACK_START should be defined in the linker script. # |
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| 44 | |
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| 45 | movd $__STACK_START, (sp) |
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| 46 | |
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| 47 | movd $__ISTACK_START, (r1,r0) |
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| 48 | lprd (r1,r0), isp |
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| 49 | |
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| 50 | #----------------------------------------------------------------------------# |
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| 51 | # Initialize the default sections according to the linker script. # |
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| 52 | |
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| 53 | # bal (ra), __init_bss_data |
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| 54 | |
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| 55 | #----------------------------------------------------------------------# |
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| 56 | # Set the Extended Dispatch bit in the CFG register. This is the # |
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| 57 | # default configuration for CR16C. # |
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| 58 | |
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| 59 | spr cfg, r0 # Set dispatch table width |
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| 60 | orw $0x100, r0 |
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| 61 | lpr r0, cfg |
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| 62 | |
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| 63 | #----------------------------------------------------------------------------# |
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| 64 | |
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| 65 | |
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| 66 | #----------------------------------------------------------------------------# |
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| 67 | # Handle global and static constructurs execution and setup # |
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| 68 | # destructors to be called from exit. # |
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| 69 | |
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| 70 | bal (ra),__init |
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| 71 | movd $__fini@c, (r3,r2) |
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| 72 | bal (ra), _atexit |
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| 73 | |
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| 74 | #----------------------------------------------------------------------------# |
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| 75 | # Jump to the main function in your application. # |
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| 76 | |
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| 77 | #ifdef __INT32__ |
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| 78 | movd $0, (r3,r2) # Number of arguments |
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| 79 | movd $0, (r5,r4) # conatins pointer to argument string. |
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| 80 | #else |
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| 81 | movw $0, r2 # Number of arguments |
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| 82 | movd $0, (r4,r3) # conatins pointer to argument string. |
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| 83 | #endif |
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| 84 | bal (ra), _main |
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| 85 | |
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| 86 | #----------------------------------------------------------------------------# |
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| 87 | # Upon returning from the main function (if it isn't an infinite loop), # |
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| 88 | # jump to the exit function. The exit function is located in the # |
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| 89 | # library 'libc.a'. # |
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| 90 | |
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| 91 | #ifdef __INT32__ |
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| 92 | movd (r1,r0), (r3,r2) # _main return value gets forwarded. |
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| 93 | #else |
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| 94 | movw r0, r2 # _main return value gets forwarded. |
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| 95 | #endif |
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| 96 | br _exit # returns control to the functional simulator. |
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| 97 | |
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| 98 | |
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