M xywrun.c → xywrun.c

@@ -57,19 +57,29 @@ xyw_word *pc = &pc_storage;
 xyw_word *xw = &xw_storage;
 xyw_word *yw = &yw_storage;
 
-//// Helpers to manage 2-byte values to memory (big-endian)
+//// Read/write memory helpers
 
-static inline xyw_word mget(xyw_word addr)
+static inline xyw_word readw(xyw_word addr)
 {
     return ((xyw_word)xyw_memory[addr] << 8) | xyw_memory[addr + 1];
 }
 
-static inline void mset(xyw_word addr, xyw_word val)
+static inline void writew(xyw_word addr, xyw_word val)
 {
     xyw_memory[addr] = (val >> 8) & 0xFF;
     xyw_memory[addr + 1] = val & 0xFF;
 }
 
+static inline xyw_byte read(xyw_word addr)
+{
+    return xyw_memory[addr];
+}
+
+static inline void write(xyw_word addr, xyw_byte val)
+{
+    xyw_memory[addr] = val;
+}
+
 //// System stack management
 
 static xyw_word ss_popw()
@@ -79,8 +89,8 @@ {
         xyw_memory[SYSTEM_ERROR] = XYW_ERROR_STACK_UNDERFLOW;
         return -1;
     }
-    xyw_word val = mget(SYSTEM_STACK_START + (*s) - 2);
-    mset(SYSTEM_STACK_START + (*s) - 2, 0);
+    xyw_word val = readw(SYSTEM_STACK_START + (*s) - 2);
+    writew(SYSTEM_STACK_START + (*s) - 2, 0);
     (*s) -= 2;
     return val;
 }
@@ -92,7 +102,7 @@ {
         xyw_memory[SYSTEM_ERROR] = XYW_ERROR_STACK_OVERFLOW;
         return;
     }
-    mset(SYSTEM_STACK_START + *s, val);
+    writew(SYSTEM_STACK_START + *s, val);
     (*s) += 2;
 }
 
@@ -116,7 +126,7 @@ {
         xyw_memory[SYSTEM_ERROR] = XYW_ERROR_STACK_OVERFLOW;
         return;
     }
-    mset(USER_STACK_START + *u, val);
+    writew(USER_STACK_START + *u, val);
     xyw_dbg(" => %04X\n", val);
     (*u) += 2;
 }
@@ -141,8 +151,8 @@ {
         xyw_memory[SYSTEM_ERROR] = XYW_ERROR_STACK_UNDERFLOW;
         return -1;
     }
-    xyw_word val = mget(USER_STACK_START + (*u) - 2);
-    mset(USER_STACK_START + (*u) - 2, 0);
+    xyw_word val = readw(USER_STACK_START + (*u) - 2);
+    writew(USER_STACK_START + (*u) - 2, 0);
     (*u) -= 2;
     return val;
 }
@@ -200,7 +210,7 @@ #define OPC_PSH(opc) { \
     case opc: { (*pc)++; us_push(xyw_memory[*pc]); } break; \
     case XYW_MODE_X|opc: { us_push(*x); } break; \
     case XYW_MODE_Y|opc: { us_push(*y); } break; \
-    case XYW_MODE_W|opc: { (*pc)++; us_pushw(mget(*pc)); (*pc)++; } break; \
+    case XYW_MODE_W|opc: { (*pc)++; us_pushw(readw(*pc)); (*pc)++; } break; \
     case XYW_MODE_X|XYW_MODE_W|opc: { us_pushw(*xw); } break; \
     case XYW_MODE_Y|XYW_MODE_W|opc: { us_pushw(*yw); } break; \
 }
@@ -238,9 +248,9 @@ #define PUSH(n) do { if (w) { us_pushw(n); } else { us_push(n); } } while(0)
 // Pop value from stack
 #define POP() (w ? us_popw() : (xyw_word)us_pop())
 // Read value from address
-#define READ(addr) (w ? mget(addr) : (xyw_byte)xyw_memory[addr])
+#define READ(addr) (w ? readw(addr) : (xyw_byte)read(addr))
 // Write value as word or byte depending on width flag 'w'
-#define WRITE(addr, val) do { if (w) { mset(addr, val); } else { xyw_memory[addr] = val; } } while(0)
+#define WRITE(addr, val) w ? writew(addr, val) : write(addr, (xyw_byte)(val))
 
 // clang-format on
 int run(const char *input)