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ram.c
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ram.c
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#include "ram.h"
#include "common.h"
#include <stdio.h>
#include "log.h"
#include "interface.h"
#include <stdint.h>
#include <stdlib.h>
#define RAM_SIZE 0x1000000 // 10 MB
FILE* ram_file_ptr;
char* ram;
uint16_t *ram_half;
uint32_t *ram_word;
uint64_t *ram_double;
struct ram_req iram_req, dram_req;
struct ram_resp iram_resp, dram_resp;
void init_ram() {
// init ram if a ram path is provided
if ((ram_file_ptr = fopen(ram_file, "r")) == NULL) {
LOG("cannot load ram file");
}
int c, load_size = 0;
ram = (char *)malloc(RAM_SIZE);
while ((c = fgetc(ram_file_ptr)) != EOF) {
ram[load_size++] = c;
assert(load_size < RAM_SIZE);
}
ram_word = (uint32_t *)ram;
ram_half = (uint16_t *)ram;
ram_double = (uint64_t *)ram;
}
void iram_step() {
// handle instruction memory
assert(iram_req.wr == 0);
if (iram_req.valid && iram_req.size > 1) {
// does not need to clear rdata for it will be fully overriden
for (int i = 0; i < (1 << (iram_req.size - 2)); ++i) {
iram_resp.rdata[i] = ram_word[(iram_req.addr >> 2) + i];
}
} else {
iram_resp.rdata[0] = 0;
for (int i = (1 << iram_req.size) - 1; i >= 0; --i) {
iram_resp.rdata[0] = (iram_resp.rdata[0] << 8) | (ram[iram_req.addr + i]);
}
}
}
void dram_step() {
// handle data memory
if (dram_req.valid) {
if (dram_req.wr) {
// cannot write more than 4 bytes in a single op
assert(dram_req.size < 3);
assert(!((dram_req.addr & 0x3) && (dram_req.size == 2)));
assert(!((dram_req.addr & 0x1) && (dram_req.size == 1)));
uint32_t wdata = dram_req.wdata;
for (int i = 0; i < (1 << dram_req.size); ++i) {
ram[dram_req.addr + i] = wdata & 0xff;
wdata >>= 8;
}
} else {
if (dram_req.size > 1) {
// does not need to clear rdata for it will be fully overriden
for (int i = 0; i < (1 << (dram_req.size - 2)); ++i) {
dram_resp.rdata[i] = ram_word[(dram_req.addr >> 2) + i];
}
} else {
iram_resp.rdata[0] = 0;
for (int i = (1 << dram_req.size) - 1; i >= 0; --i) {
dram_resp.rdata[0] = (dram_resp.rdata[0] << 8) | (ram[dram_req.addr + i]);
}
}
}
}
}