diff --git a/acs_interface/ZMEMORY.acs b/acs_interface/ZMEMORY.acs new file mode 100644 index 0000000..4a1c6d4 --- /dev/null +++ b/acs_interface/ZMEMORY.acs @@ -0,0 +1,18 @@ +#library "ZMEMORY" +#include "zcommon.acs" + +//Simple linked list implementation of malloc + +//Memory space +global int 63:memory[]; + +//NULL "pointer" +#libdefine nullptr 0 + +//Allocated size bytes in the memory space +function int malloc (int size) {return 0;} + +//Frees an allocated block in the memory space. +//There are no safeguards in this function to guess whether or not the free is +// valid, so be careful. +function int free (int p_ptr) {return 0;} diff --git a/src/LOADACS.txt b/src/LOADACS.txt new file mode 100644 index 0000000..6936c32 --- /dev/null +++ b/src/LOADACS.txt @@ -0,0 +1 @@ +ZMEMORY diff --git a/src/acs_source/ZMEMORY.acs b/src/acs_source/ZMEMORY.acs new file mode 100644 index 0000000..2f5befd --- /dev/null +++ b/src/acs_source/ZMEMORY.acs @@ -0,0 +1,156 @@ +#library "ZMEMORY" +#include "zcommon.acs" + +//Simple linked list implementation of malloc + +global int 63:memory[]; + +#libdefine nullptr 0 + +#define malloc_allocated 0 +#define malloc_size 1 +#define malloc_next_header 2 +#define malloc_prev_header 3 +#define malloc_num_header_properties 4 + +#define p_malloc_init_flag_location 0 +#define p_malloc_first_header_location 1 + +function int malloc (int size) { + log(s:"Invoked malloc"); + //Do the setup on the first run of this function. + if(memory[p_malloc_init_flag_location] == FALSE) { //Default values for global values is 0, so this is true. + memory[p_malloc_init_flag_location] = TRUE; + memory[p_malloc_first_header_location+malloc_allocated] = FALSE; + memory[p_malloc_first_header_location+malloc_size] = -1; //"infinite" + memory[p_malloc_first_header_location+malloc_next_header] = nullptr; //nullptr + memory[p_malloc_first_header_location+malloc_prev_header] = nullptr; //nullptr + } + + int p_previous_header = nullptr; + int p_current_header = p_malloc_first_header_location; + int p_retval = nullptr; + + while(p_retval == nullptr) { + int memalloced = memory[p_current_header+malloc_allocated]; + int memsize = memory[p_current_header+malloc_size]; + if(memsize == -1) { //The end of the list. + memory[p_current_header+malloc_allocated] = TRUE; + memory[p_current_header+malloc_size] = size; + memory[p_current_header+malloc_next_header] = p_current_header+malloc_num_header_properties+size; //New EOL + memory[p_current_header+malloc_prev_header] = p_previous_header; + + //Retrieve the return value while we are at the allocated space. + p_retval = p_current_header+malloc_num_header_properties; + + //Remember to initialize the new end list node. + p_previous_header = p_current_header; //This is the header previous to the EOL. + p_current_header = memory[p_current_header+malloc_next_header]; + //Set the tail node constants. + memory[p_current_header+malloc_allocated] = FALSE; + memory[p_current_header+malloc_size] = -1; + memory[p_current_header+malloc_next_header] = nullptr; + memory[p_current_header+malloc_prev_header] = p_previous_header; + } else if(memsize >= size && memalloced == FALSE) { //There is room here AND it isn't in use, + memory[p_current_header+malloc_allocated] = TRUE; + //The size isn't modified because we are re-using an existing space. + // It would be a good idea to check just how large this space is and act accordingly rather + // than using a 500 indexes large space for a 4 indexes large object. + // Objects allocated in a doom mod probably won't be outside the 1-16 indexes range so it + // should still be fine for most applications. + //The next header isn't changed either for the same reason. + if(memsize >= (size+malloc_num_header_properties+5)) { //Assume that 5 is the smallest useful allocation size. + int p_split_newheader = p_current_header+malloc_num_header_properties+size; //Just to the end of the allocation. + memory[p_split_newheader+malloc_allocated] = FALSE; + memory[p_split_newheader+malloc_size] = memory[p_current_header+malloc_size]-malloc_num_header_properties-size; + memory[p_split_newheader+malloc_next_header] = memory[p_current_header+malloc_next_header]; + memory[p_split_newheader+malloc_prev_header] = p_current_header; + memory[p_current_header+malloc_next_header] = p_split_newheader; //The header whose block was split should have its next pointer set to its other half. + memory[p_current_header+malloc_size] = size; //Set the size of the allocation to reflect the split. + } + + //Retrieve the return value while we are at the allocated space. + p_retval = p_current_header+malloc_num_header_properties; + } else { + //The observed node isn't useful for allocating the request. Go to the next node. + p_previous_header = p_current_header; + p_current_header = memory[p_current_header+malloc_next_header]; + } + } + + log(s:"Malloc allocated ", d:size, s:" indexes at location ", d:p_retval, s:" with header location ", d:p_current_header); + + return p_retval; +} + +function int free (int p_ptr) { + log(s:"Invoked free"); + + int p_header = p_ptr - malloc_num_header_properties; + + memory[p_header+malloc_allocated] = FALSE; + + int p_next = memory[p_header+malloc_next_header]; + int p_prev = memory[p_header+malloc_prev_header]; + + //Below is the merging of free blocks. + //It merges to the left (lower indexes) first becaue the right (larger + // indexes) has a special case. (the end of the list) + + //the previous block is unused. Merge. + if(p_prev != nullptr //This doesn't make sense if the previous block doesn't exist. + && memory[p_prev+malloc_allocated] == FALSE) { + log(s:"Free attempting merge of header ", d:p_header, s: " to the left with header ", d:p_prev); + memory[p_prev+malloc_size] += memory[p_header+malloc_size] + malloc_num_header_properties; + memory[p_prev+malloc_next_header] = p_next; //The prev header needs to know the new next. + memory[p_next+malloc_prev_header] = p_prev; //The next header needs to know the new prev. + + //Now the two blocks are the same block. requires new initializations of the + // variables for the other check to function correctly. + //The header is the result of the merge, and the prev is the one before it. + p_header = p_prev; + p_prev = memory[p_header+malloc_prev_header]; + } + + //The next block is unused. Merge. + //Note that p_next will never be a nullptr with correct usage. + if(memory[p_next+malloc_allocated] == FALSE) { + if(memory[p_next+malloc_size] == -1) { //EOL + memory[p_header+malloc_size] = -1; + memory[p_header+malloc_next_header] = nullptr; + } else { + int p_next_next = memory[p_next+malloc_next_header]; + memory[p_header+malloc_size] += memory[p_next+malloc_size] + malloc_num_header_properties; + memory[p_header+malloc_next_header] = p_next_next; //The header on the other side of the next header needs to know its new prev. + memory[p_next_next+malloc_prev_header] = p_header; //This header needs to know its new next. + } + } + + + return -1; +} + +//These are for debugging +script "memory_write" (int index, int value) { + memory[index] = value; +} + +script "memory_read" (int index) { + log(d:memory[index]); +} + +script "memory_print_allocation_list" (void) { + int p_current_header = p_malloc_first_header_location; + + while(p_current_header != nullptr) { + log(s: "Header location: ", d:p_current_header, + s:"\n Allocated flag: ", d:memory[p_current_header+malloc_allocated], + s:"\n Allocation size: ", d:memory[p_current_header+malloc_size], + s:"\n Prev header pointer: ", d:memory[p_current_header+malloc_prev_header], + s:"\n Next header pointer: ", d:memory[p_current_header+malloc_next_header], + s:"\n" + ); + + p_current_header = memory[p_current_header+malloc_next_header]; + } +}