Start on FILE i/O

src/cpu.c

@@ -1,6 +1,6 @@
 #include "cpu.h"
 
-#include "memoryMap.h"
+#include "memory.h"
 #include "opcodes.h"
 
 #define COMBINE(H, L) ((H << 8) | L)

src/file.c

@@ -0,0 +1,63 @@
+#include "file.h"
+
+#include <errno.h>
+#include <stdio.h>
+
+// Up to 256 files can be open
+FILE *files[256];
+
+int openFile(int fd, const char *path) {
+  files[fd] = fopen(path, "r+");
+  if (files[fd] == NULL) {
+    return errno;
+  }
+
+  return 0;
+}
+
+int closeFile(int fd) {
+  int ret = fclose(files[fd]);
+  if (ret != 0) {
+    return errno;
+  }
+
+  return 0;
+}
+
+int readByte(const int fd, int *data) {
+  int status = 0;
+  int count = fread(&data, 1, 1, files[fd]);
+  // Error or EOF
+  if (count != 1) {
+    int error = ferror(files[fd]);
+    int eof = feof(files[fd]);
+    if (error != 0) {
+      status = 0x2;
+    } else if (eof != 0) {
+      status = 0x1;
+    } else {
+      status = 0x4;
+    }
+  }
+
+  return status;
+}
+
+int writeByte(const int fd, const int data) {
+  int status = 0;
+  int count = fwrite(&data, 1, 1, files[fd]);
+  // Error or EOF
+  if (count != 1) {
+    int error = ferror(files[fd]);
+    int eof = feof(files[fd]);
+    if (error != 0) {
+      status = 0x2;
+    } else if (eof != 0) {
+      status = 0x1;
+    } else {
+      status = 0x4;
+    }
+  }
+
+  return status;
+}

src/main.c

@@ -46,7 +46,7 @@ int main(void) {
 
   printf("6502PC Emulator with MS Basic\n");
   printf("CTRL + G to exit\n");
-  printf("WOZMON available, BASIC at DF6A\n");
+  printf("WOZMON available, BASIC at E032\n");
 
   clock_gettime(CLOCK_MONOTONIC, &emulationStart);
 

src/memory.c

@@ -1,4 +1,4 @@
-#include "memoryMap.h"
+#include "memory.h"
 
 uint8_t readMemory(uint16_t address, uint8_t *ram, uint8_t *rom) {
   // RAM/ROM
@@ -16,10 +16,18 @@ uint8_t readMemory(uint16_t address, uint8_t *ram, uint8_t *rom) {
       case KEYBOARD_ADDRESS: {
         return getChar();
       }
+
       case ROM_BANKED_OUT: {
         return ram[IO_BASE + ROM_BANKED_OUT];
       }
 
+      case FILE_DATA: {
+        return ram[IO_BASE + FILE_DATA];
+      }
+      case FILE_STATUS: {
+        return ram[IO_BASE + FILE_STATUS];
+      }
+
       default:
         break;
     }
@@ -55,6 +63,33 @@ void writeMemory(uint16_t address, uint8_t value, uint8_t *ram) {
       ram[IO_BASE + ROM_BANKED_OUT] = value;
       break;
 
+    case FILE_COMMAND: {
+      switch (ram[IO_BASE + FILE_COMMAND]) {
+        case COMMAND_OPEN: {
+          ram[IO_BASE + FILE_STATUS] = 0;
+          ram[IO_BASE + FILE_STATUS] = openFile(ram[IO_BASE + FILE_DESCRIPTOR], (const char *)&ram[IO_BASE + FILE_DATA]);
+          break;
+        }
+        case COMMAND_CLOSE: {
+          ram[IO_BASE + FILE_STATUS] = 0;
+          ram[IO_BASE + FILE_STATUS] = closeFile(ram[IO_BASE + FILE_DESCRIPTOR]);
+          break;
+        }
+
+        default:
+          break;
+      }
+      break;
+    }
+    case FILE_DESCRIPTOR: {
+      ram[IO_BASE + FILE_DESCRIPTOR] = value;
+      break;
+    }
+    case FILE_DATA: {
+      ram[IO_BASE + FILE_DATA] = value;
+      break;
+    }
+
     default:
       break;
   }

src/screen.c

@@ -1,38 +1,38 @@
-#include "io.h"
-
-#include <stdio.h>
-#include <stdlib.h>
-
-int putChar(uint8_t c) {
-  int _c = putchar(c);
-  fflush(stdout);
-
-  return _c;
-}
-
-int getChar(void) {
-  clearerr(stdin);
-
-  int c = getchar();
-
-  // Specifically send FF for EOF to trigger echo cancellation
-  if (c == EOF) {
-    return 0xFF;
-  }
-
-  // BASIC expects CR always
-  if (c == '\n') {
-    return '\r';
-  }
-
-  // BASIC is uppercase only
-  if (c >= 'a' && c <= 'z') {
-    c = c - 'a' + 'A';
-  }
-
-  if (c == 0x07) {
-    exit(EXIT_SUCCESS);
-  }
-
-  return c;
+#include "screen.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+
+int putChar(uint8_t c) {
+  int _c = putchar(c);
+  fflush(stdout);
+
+  return _c;
+}
+
+int getChar(void) {
+  clearerr(stdin);
+
+  int c = getchar();
+
+  // Specifically send FF for EOF to trigger echo cancellation
+  if (c == EOF) {
+    return 0xFF;
+  }
+
+  // BASIC expects CR always
+  if (c == '\n') {
+    return '\r';
+  }
+
+  // BASIC is uppercase only
+  if (c >= 'a' && c <= 'z') {
+    c = c - 'a' + 'A';
+  }
+
+  if (c == 0x07) {
+    exit(EXIT_SUCCESS);
+  }
+
+  return c;
 }