| 1 | /* Author : Rick van der Zwet
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| 2 | * S-number : 0433373
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| 3 | * Version : $Id: datapath.c 365 2007-12-03 08:54:04Z rick $
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| 4 | * Copyright : FreeBSD Licence
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| 5 | * Description : Memory 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 "datapath.h"
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| 12 | #include "imm.h"
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| 13 | #include "constant.h"
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| 14 | #include "memory.h"
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| 15 |
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| 16 | word
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| 17 | select_sx(const sx_control_t control)
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| 18 | {
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| 19 | word out=0;
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| 20 | switch (control)
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| 21 | {
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| 22 | case NO_COMPONENT:
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| 23 | out = 0;
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| 24 | break;
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| 25 | case A:
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| 26 | out = a;
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| 27 | break;
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| 28 | case B:
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| 29 | out = b;
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| 30 | break;
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| 31 | case TEMP:
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| 32 | out = temp;
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| 33 | break;
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| 34 | case TEMP2:
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| 35 | out = temp2;
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| 36 | break;
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| 37 | case PC:
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| 38 | out = pc;
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| 39 | break;
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| 40 | case MAR:
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| 41 | out = mar;
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| 42 | break;
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| 43 | case MDR:
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| 44 | out = mdr;
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| 45 | break;
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| 46 | case CONST:
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| 47 | out = constant;
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| 48 | break;
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| 49 | case IMM:
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| 50 | out = imm;
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| 51 | break;
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| 52 | default:
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| 53 | fprintf(stderr, "Switch '%i' not implemented\n", control);
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| 54 | exit(EX_SOFTWARE);
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| 55 | break;
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| 56 | };
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| 57 | return (out);
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| 58 | }
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| 59 |
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| 60 | void
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| 61 | update_state(control_t control)
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| 62 | {
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| 63 | word temp_destbus;
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| 64 | word temp_mem;
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| 65 |
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| 66 | constant = constant_call(control.constant);
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| 67 | imm = imm_call(ir, control.ir);
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| 68 |
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| 69 | /* Going to ALU if activated */
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| 70 | word in1 = 0;
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| 71 | word in2 = 0;
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| 72 | if (control.alu_unit == ALU_STALLED) {
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| 73 | temp_destbus = 0;
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| 74 | } else {
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| 75 | in1 = select_sx(control.s1);
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| 76 | in2 = select_sx(control.s2);
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| 77 | temp_destbus = alu(in1, in2, control.alu_unit);
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| 78 | }
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| 79 |
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| 80 | if (control.c == WRITE)
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| 81 | c = temp_destbus;
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| 82 | if (control.temp == WRITE)
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| 83 | temp = temp_destbus;
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| 84 | if (control.temp2 == WRITE)
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| 85 | temp2 = temp_destbus;
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| 86 | if (control.pc == WRITE)
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| 87 | pc = temp_destbus;
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| 88 | if (control.mar == WRITE)
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| 89 | mar = temp_destbus;
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| 90 | if (control.mdr == WRITE) {
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| 91 | if (control.mux == DATAPATH)
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| 92 | mdr = temp_destbus;
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| 93 | else if (control.mux == MEMORY)
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| 94 | mdr = temp_mem;
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| 95 | else {
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| 96 | fprintf(stderr, "Mux control not defined\n");
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| 97 | exit(EX_SOFTWARE);
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| 98 | }
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| 99 | }
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| 100 |
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| 101 | /* Memory actions */
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| 102 | if (control.memory != MEM_STALLED) {
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| 103 | mem_busy = TRUE;
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| 104 | temp_mem = mem_operation(mar, mdr, control.memory);
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| 105 | if (control.ir == WRITE)
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| 106 | ir = temp_mem;
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| 107 | if (control.mdr == WRITE && control.mux == MEMORY)
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| 108 | mdr = temp_mem;
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| 109 | }
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| 110 |
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| 111 |
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| 112 | /* Register actions */
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| 113 | if (control.a == WRITE && ((control.reg & 1) != 0))
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| 114 | a = reg[control.register_address_a];
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| 115 | if (control.b == WRITE && ((control.reg & 2) != 0))
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| 116 | b = reg[control.register_address_b];
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| 117 | if ((control.reg & 4) != 0)
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| 118 | reg[control.register_address_c] = c;
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| 119 | }
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