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Slightly reorganized cache_access. Moved set re-linking to new function update_set.

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Amend: Missed one instance of changed variable name.
This commit is contained in:
Jacob 2016-04-29 17:57:02 -04:00
parent 93801e248b
commit 8e948abbc3
1 changed files with 28 additions and 16 deletions
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44
csim.c
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@ -73,6 +73,7 @@ void print_set(linked_line* line);
/* Cache access functions */ /* Cache access functions */
char cache_access(linked_line** cache, long address, int set_bits, int block_offset_bits, long num_lines); char cache_access(linked_line** cache, long address, int set_bits, int block_offset_bits, long num_lines);
linked_line* find_line(linked_line* set_head, long tag); linked_line* find_line(linked_line* set_head, long tag);
linked_line* update_set(linked_line* old_head, linked_line* new_head);
//linked_line* move_to_head(linked_line* new_head, linked_line* old_head); //linked_line* move_to_head(linked_line* new_head, linked_line* old_head);
@ -396,37 +397,28 @@ void print_set(linked_line* line)
char cache_access(linked_line** cache, long address, char cache_access(linked_line** cache, long address,
int set_bits, int block_offset_bits, long num_lines) int set_bits, int block_offset_bits, long num_lines)
{ {
char out; char operation;
long tag = address >> set_bits >> block_offset_bits; long tag = address >> set_bits >> block_offset_bits;
long set = (address >> block_offset_bits) & ((1 << set_bits) - 1); long set = (address >> block_offset_bits) & ((1 << set_bits) - 1);
linked_line* set_head = cache[set]; linked_line* set_head = cache[set];
linked_line* line = find_line(set_head, tag); linked_line* line = find_line(set_head, tag);
if (!line->validity) { if (!line->validity) {
out = 'M'; operation = 'M';
} }
else if (line->tag == tag) { else if (line->tag == tag) {
out = 'H'; operation = 'H';
} }
else { else {
out = 'E'; operation = 'E';
}
if(!(line == set_head)) {
line->newer->older = line->older;
if(line->older) {
line->older->newer = line->newer;
}
line->newer = NULL;
line->older = set_head;
set_head->newer = line;
cache[set] = line;
} }
line->tag = tag; line->tag = tag;
line->validity = 1; line->validity = 1;
return out; cache[set] = update_set(set_head, line);
return operation;
} }
/** /**
@ -448,4 +440,24 @@ linked_line* find_line(linked_line* line, long tag)
} }
} }
/**
Updates the use order of a set by moving the line being accessed in front of
the previously-accessed line and linking the neighbors of the new head.
@param old_head The previous most-recently modified line of the set.
@param new_head The line of the set being accessed.
@return new_head
*/
linked_line* update_set(linked_line* old_head, linked_line* new_head) {
if(!(new_head == old_head)) {
new_head->newer->older = new_head->older;
if(new_head->older) {
new_head->older->newer = new_head->newer;
}
new_head->newer = NULL;
new_head->older = old_head;
old_head->newer = new_head;
}
return new_head;
}