Added a disassembler which is still very buggy. Also fixed some bugs with the opcode mask getting function.

2022-08-26 21:41:02 +00:00
parent e4a191a17e
commit 0785f21805
8 changed files with 153 additions and 38 deletions
@@ -0,0 +1,110 @@
+#include "../includes/disass.h"
+
+const unsigned char* Image;
+const unsigned char COPYMASKREG = 0x20;
+const unsigned char COPYMASKADD = 0xA0;
+const unsigned char ADDMASK     = 0x40;
+const unsigned char SUBMASK     = 0x60;
+const unsigned char CMPMASK     = 0x80;
+
+const unsigned char REGMASK     = 0x00;//0x18; //0001 1000
+const unsigned char CONSTMASK   = 0x08; //0000 1000
+const unsigned char ADDRESSMASK = 0x10; //0001 0000
+
+int IsRegisterPattern(unsigned char pattern, unsigned char lexeme[2]);
+
+void Disassemble(unsigned char image[HIGHMEMORY]) {
+    Image = image;
+    int position = 0;
+    unsigned char lexeme[3] = { 0 };
+    unsigned char lexem2[8] = { 0 };
+
+    unsigned char instruction = image[position];
+
+    while(instruction != 0) {
+        //1110 0000
+        unsigned char masked = instruction & 0xE0;
+
+        if (masked) {
+            IsRegisterPattern(instruction & 0x07, lexeme);
+            unsigned char parameter = instruction & 0x18;
+
+            if (!parameter) {
+                position++;
+                IsRegisterPattern(Image[position], lexem2);
+            } else if (parameter == CONSTMASK) {
+                
+                lexem2[0] = 4 >> Image[position] | 0x30;
+                lexem2[1] = Image[position] | 0x30;
+                position++;
+            }
+            else if (parameter == ADDRESSMASK) {
+                //snprintf(lexem2, sizeof lexem2, "%#04X", Image[position]);
+                lexem2[0] = 'X';
+            }
+
+            //If the top bits are set
+            if (masked & COPYMASKREG) {
+                printf("copy %s, %d\n", lexeme, Image[position]);
+            }
+            else if (masked & COPYMASKADD) {
+                printf("CMP1\n");
+            }
+            else if (masked & ADDMASK) {
+                printf("CMP2\n");
+            }
+            else if (masked & SUBMASK) {
+                printf("CMP3\n");
+            }
+            else if (masked & CMPMASK) {
+                printf("CMP\n");
+            }
+            else {
+                fprintf(stderr, "[Error] Unknown opcode %#02X\n", masked);
+                exit(1);
+            }
+        }
+
+        instruction = Image[position++];
+
+        memset(lexem2, '\0', sizeof lexem2);
+        memset(lexeme, '\0', sizeof lexeme);
+    }
+}
+
+int IsRegisterPattern(unsigned char pattern, unsigned char lexeme[2]) {
+    if (pattern > 8) return 0;
+    //The registers' bit patterns are zero indexed, so 'r1' is '000'
+    //but 'r8' is '111' and so forth.
+    pattern++;
+
+    lexeme[0] = 'r';
+    lexeme[1] = pattern | 0x30;
+    return 1;
+}
+/*
+//REG       XXX0 0XXX 1010 1111
+//Constant  XXX0 1XXX
+//Address   XXX1 0XXX
+    NOP  - 0000 0000 NOP
+    JZ   - 0000 0001 JZ Address
+    INT  - 0000 0010 INT Constant
+    YLD  - 0000 0011 YLD
+    RET  - 0000 0100 RET
+    CALL - 0000 0101 CALL Address
+    JMP  - 0000 0110 JMP Address
+    IN   - 0000 0111 IN Constant
+    OUT  - 0000 1000 OUT Constant
+    COPY - 0010 0XXX COPY REG, REG
+         - 0010 1XXX COPY REG, Constant
+         - 0011 0XXX COPY REG, Address
+         - 1010 0XXX COPY Address, REG
+         - 1010 1XXX COPY Address, Constant
+         - 1011 0XXX COPY Address, Address
+    ADD  - 0100 0XXX ADD REG, REG
+         - 0100 1XXX ADD REG, Constant
+    SUB  - 0110 0XXX SUB REG, REG
+         - 0110 1XXX SUB REG, Constant
+    CMP  - 1000 0XXX CMP REG, REG
+         - 1000 1XXX CMP REG, Constant
+         - 1001 0XXX CMP REG, Address */