72 lines
1.1 KiB
C
72 lines
1.1 KiB
C
#include "top.h"
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#include "queue.h"
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empty_queue(q)
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register queue q;
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{
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q->head = q->tail = (instr_p) 0;
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q->qlen = 0;
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}
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int empty(q)
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queue q;
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{
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return q->qlen == 0;
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}
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remove_head(q)
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register queue q;
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{
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if ( (q->head = q->head->fw) == (instr_p) 0) {
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q->tail = (instr_p) 0;
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} else {
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q->head->bw = (instr_p) 0;
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}
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q->qlen--;
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}
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add(q,instr)
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register queue q;
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register instr_p instr;
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{
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if (q->qlen++ == 0) {
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q->head = q->tail = instr;
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instr->bw = (instr_p) 0;
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} else {
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q->tail->fw = instr;
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instr->bw = q->tail;
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q->tail = instr;
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}
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instr->fw = (instr_p) 0;
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}
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insert(q,instr)
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register queue q;
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register instr_p instr;
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{
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if (q->qlen++ == 0) {
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q->head = q->tail = instr;
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instr->fw = (instr_p) 0;
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} else {
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q->head->bw = instr;
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instr->fw = q->head;
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q->head = instr;
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}
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instr->bw = (instr_p) 0;
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}
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join_queues(q1,q2)
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register queue q1,q2;
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{
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if (q1->qlen > 0) {
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q2->qlen += q1->qlen;
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q1->tail->fw = q2->head;
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if (q2->qlen > 0) {
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q2->head->bw = q1->tail;
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} else {
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q2->tail = q1->tail;
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}
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q2->head = q1->head;
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empty_queue(q1);
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}
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}
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