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Last change
on this file since 3 was 2, checked in by Rick van der Zwet, 15 years ago |
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Initial import of data of old repository ('data') worth keeping (e.g. tracking
means of URL access statistics)
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Property svn:executable
set to
*
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File size:
1.7 KB
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| 1 | /* Author : Rick van der Zwet
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| 2 | * S-number : 0433373
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| 3 | * Version : $Id: alu.c 364 2007-12-03 07:23:37Z rick $
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| 4 | * Copyright : FreeBSD Licence
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| 5 | * Description : ALU unit
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| 6 | */
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| 7 |
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| 8 | #include <stdlib.h>
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| 9 | #include <stdio.h>
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| 10 | #include <sysexits.h>
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| 11 | #include "alu.h"
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| 12 |
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| 13 | word
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| 14 | alu_sra(const word in1, const word in2)
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| 15 | {
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| 16 | word out = 0;
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| 17 | out = in1 >> in2;
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| 18 | /* Find out wether high order bit was set */
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| 19 | if (in1 >> (BITSIZE(out) - 1) == 0x1) {
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| 20 | /* Set bit in2 till high-order to 1 */
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| 21 | int i = BITSIZE(out) - in2;
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| 22 | for (; i < BITSIZE(out); i++)
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| 23 | out = out | (1 << i);
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| 24 | }
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| 25 | return (out);
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| 26 | }
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| 27 |
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| 28 | word
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| 29 | alu(word in1, word in2, alu_control_t action)
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| 30 | {
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| 31 | word out = 0;
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| 32 | switch (action) {
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| 33 | case ADD:
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| 34 | out = in1 + in2;
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| 35 | break;
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| 36 | case AND:
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| 37 | out = in1 & in2;
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| 38 | break;
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| 39 | case NOR:
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| 40 | out = ~(in1 | in2);
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| 41 | break;
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| 42 | case OR:
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| 43 | out = in1 | in2;
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| 44 | break;
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| 45 | case PassS1:
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| 46 | out = in1;
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| 47 | break;
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| 48 | case PassS2:
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| 49 | out = in2;
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| 50 | break;
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| 51 | case SLL:
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| 52 | out = in1 << in2;
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| 53 | break;
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| 54 | case SRA:
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| 55 | out = alu_sra(in1, in2);
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| 56 | break;
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| 57 | case SRL:
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| 58 | out = in1 >> in2;
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| 59 | break;
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| 60 | case SUB:
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| 61 | out = in1 - in2;
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| 62 | break;
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| 63 | case XOR:
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| 64 | out = in1 ^ in2;
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| 65 | break;
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| 66 | default:
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| 67 | fprintf(stderr,"Requested alu-action not implemented\n");
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| 68 | exit(EX_SOFTWARE);
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| 69 | break;
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| 70 | };
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| 71 |
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| 72 | /* Set signals */
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| 73 | if (out < 0) {
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| 74 | zero = FALSE;
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| 75 | negative = TRUE;
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| 76 | } else if (out == 0) {
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| 77 | zero = TRUE;
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| 78 | negative = FALSE;
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| 79 | } else {
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| 80 | zero = FALSE;
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| 81 | negative = FALSE;
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| 82 | }
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| 83 |
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| 84 | return(out);
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| 85 | }
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