Root/lm32/logic/sakc/firmware/boot0-serial/crt0ram.S

1/*
2 * LatticeMico32 C startup code.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
14 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
16 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
17 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
18 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
19 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
20 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
21 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
22 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
23 * SUCH DAMAGE.
24 */
25
26/* Exception handlers - Must be 32 bytes long. */
27        .section .text, "ax", @progbits
28        .global _start
29        .global irq_enable, irq_disable, irq_mask, jump, halt
30_start:
31_reset_handler:
32    xor r0, r0, r0
33    wcsr IE, r0
34    mvhi r1, hi(_reset_handler)
35    ori r1, r1, lo(_reset_handler)
36    wcsr EBA, r1
37    calli _crt0
38    nop
39    nop
40
41_crt0:
42    /* Setup stack and global pointer */
43    mvhi sp, hi(_fstack)
44    ori sp, sp, lo(_fstack)
45    mvhi gp, hi(_gp)
46    ori gp, gp, lo(_gp)
47
48    /* Clear BSS */
49    mvhi r1, hi(_fbss)
50    ori r1, r1, lo(_fbss)
51    mvhi r3, hi(_ebss)
52    ori r3, r3, lo(_ebss)
53.clearBSS:
54    be r1, r3, .callMain
55    sw (r1+0), r0
56    addi r1, r1, 4
57    bi .clearBSS
58    
59.callMain:
60    mvi r1, 0
61    mvi r2, 0
62    mvi r3, 0
63    calli main
64
65irq_enable:
66    mvi r1, 1
67    wcsr IE, r1
68    ret
69
70irq_mask:
71    mvi r1, 0x0000000f
72    wcsr IM, r1
73    ret
74    
75irq_disable:
76    mvi r1, 0
77    wcsr IE, r1
78    ret
79
80jump:
81    b r1
82
83halt:
84    bi halt
85
86

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