87 lines
2.6 KiB
C
87 lines
2.6 KiB
C
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#include <stdint.h>
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#include <stdio.h>
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struct AddressSpace_s {
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// A pointer to a ROM array. The array can vary in length.
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uint8_t *rom;
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// The size of ROM.
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uint32_t romSize;
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// A pointer to a RAM array. The array can vary in length.
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uint8_t *ram;
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// The size of RAM.
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uint32_t ramSize;
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};
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typedef struct AddressSpace_s AddressSpace;
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AddressSpace create_address_space(int romSize, int ramSize) {
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uint8_t rom[romSize];
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uint8_t ram[ramSize];
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AddressSpace addressSpace = { rom, romSize, ram, ramSize };
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return addressSpace;
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}
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int read_address_space(const AddressSpace *addressSpace, uint32_t address, const int n, uint8_t *dest) {
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uint32_t romSize = addressSpace->romSize;
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uint32_t ramSize = addressSpace->ramSize;
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if (address < romSize) {
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if (address + n < romSize) {
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fprintf(stderr, "Reading %d bytes from %d will exceed ROM address space of %d\n", n, address, romSize); // TODO maybe move to perror
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return 1;
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} else {
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for (int i=0; i<n; i++) {
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dest[i] = addressSpace->rom[address + i];
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}
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}
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} else if (address < romSize + ramSize) {
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if (address + n < romSize + ramSize) {
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fprintf(stderr, "Reading %d bytes from %d (total %d) will exceed RAM address space of %d (total %d)\n", n, address, address + romSize, ramSize, romSize + ramSize);
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return 1;
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} else {
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address -= romSize;
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for (int i=0; i<n; i++) {
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dest[i] = addressSpace->ram[address + i];
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}
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}
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} else {
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// TODO IO
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}
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return 0;
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}
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int write_address_space(const AddressSpace *addressSpace, uint32_t address, const int n, uint8_t *src) {
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uint32_t romSize = addressSpace->romSize;
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uint32_t ramSize = addressSpace->ramSize;
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if (address < romSize) {
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if (address + n < romSize) {
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fprintf(stderr, "Writing %d bytes to %d will exceed ROM address space of %d\n", n, address, romSize);
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return 1;
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} else {
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for (int i=0; i<n; i++) {
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addressSpace->rom[address + i] = src[i];
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}
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}
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} else if (address < romSize + ramSize) {
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if (address + n < romSize + ramSize) {
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fprintf(stderr, "Writing %d bytes to %d (total %d) will exceed RAM address space of %d (total %d)\n", n, address, address + romSize, ramSize, romSize + ramSize);
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return 1;
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} else {
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address -= romSize;
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for (int i=0; i<n; i++) {
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addressSpace->ram[address + i] = src[i];
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}
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}
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} else {
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// TODO IO
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}
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return 0;
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}
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