# crt.asm
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# crt.asm
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# C RunTime:
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# C RunTime:
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# Used for initialization of small data
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# Used for initialization of small data
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# anchors and stack for programs compiled using
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# anchors and stack for programs compiled using
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# Xilinx Gnu Tools.
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# Xilinx Gnu Tools.
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# Used for initialization of user's bss area
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# Used for initialization of user's bss area
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# All external and static variables are initialized
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# All external and static variables are initialized
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.globl _start
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.globl _start
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.align 2
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.align 2
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.ent _start
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.ent _start
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_start:
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_start:
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nop /* to help simulation external program without block ram */
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/* todo : initialize system vectors */
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/* todo : initialize system vectors */
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/* Set the Small Data Anchors and the Stack pointer */
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/* Set the Small Data Anchors and the Stack pointer */
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la r13, r0, _SDA_BASE_
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la r13, r0, _SDA_BASE_
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la r2, r0, _SDA2_BASE_
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la r2, r0, _SDA2_BASE_
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la r1, r0, _stack # stack is at end of heap
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la r1, r0, _stack # stack is at end of heap
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_crtinit: /* clear sbss */
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_crtinit: /* clear sbss */
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addi r6,r0,__sbss_start /* SBSS beginning */
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addi r6,r0,__sbss_start /* SBSS beginning */
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addi r7,r0,__sbss_end /* SBSS end */
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addi r7,r0,__sbss_end /* SBSS end */
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rsub r18,r6,r7 /* Compare */
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rsub r18,r6,r7 /* Compare */
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blei r18,.Lendsbss
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blei r18,.Lendsbss
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.Lloopsbss:
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.Lloopsbss:
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sw r0,r6,r0
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sw r0,r6,r0
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addi r6,r6,4
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addi r6,r6,4
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rsub r18,r6,r7
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rsub r18,r6,r7
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bgti r18,.Lloopsbss
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bgti r18,.Lloopsbss
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.Lendsbss: /* clear bss */
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.Lendsbss: /* clear bss */
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addi r6,r0,__bss_start /* BSS beginning */
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addi r6,r0,__bss_start /* BSS beginning */
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addi r7,r0,__bss_end /* BSS end */
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addi r7,r0,__bss_end /* BSS end */
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rsub r18,r6,r7 /* Compare */
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rsub r18,r6,r7 /* Compare */
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blei r18,.Lendbss
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blei r18,.Lendbss
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.Lloopbss:
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.Lloopbss:
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sw r0,r6,r0
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sw r0,r6,r0
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addi r6,r6,4
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addi r6,r6,4
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rsub r18,r6,r7
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rsub r18,r6,r7
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bgti r18,.Lloopbss
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bgti r18,.Lloopbss
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.Lendbss:
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.Lendbss:
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brlid r15,main # enter main program (ignoring parameters: r5, r6 & r7)
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brlid r15,main # enter main program (ignoring parameters: r5, r6 & r7)
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nop # fall throught to exit
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nop # fall throught to exit
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.end _start
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.end _start
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.globl exit # exit library call
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.globl exit # exit library call
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.ent exit
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.ent exit
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exit:
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exit:
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brai 0x0 # enter monitor again...
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brai 0x0 # enter monitor again...
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.end exit
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.end exit
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