From d7c23e7bf0d409cd0c4539c223871f421c1b3320 Mon Sep 17 00:00:00 2001
From: sBubshait <s.bobshit@gmail.com>
Date: Fri, 31 May 2024 17:45:02 +0100
Subject: [PATCH] Add decode for Branch Instructions, w/ T

---
 src/decode.c | 36 ++++++++++++++++++++++++++++++++++--
 src/decode.h | 19 +++++++++++++++----
 2 files changed, 49 insertions(+), 6 deletions(-)

diff --git a/src/decode.c b/src/decode.c
index 9ee999d..a607e18 100644
--- a/src/decode.c
+++ b/src/decode.c
@@ -22,7 +22,7 @@ a64inst_instruction *decode(word wrd) {
         exit(1);
     }
 
-    word DPImmFlag = getBits(wrd, DATA_PROCESSING_DPIMM_LSB, DATA_PROCESSING_DPIMM_MSB);
+    word DPImmFlag = getBits(wrd, BRANCH_CONDITIONAL_COND_LSB, BRANCH_CONDITIONAL_COND_MSB);
     if (wrd == HALT_WORD) {
         inst->type = a64inst_HALT;
         
@@ -31,8 +31,40 @@ a64inst_instruction *decode(word wrd) {
 
     }else if (DPImmFlag == 1) {
         inst->type = a64inst_BRANCH;
+        word branchTypeFlag = getBits(wrd, BRANCH_TYPE_LSB, BRANCH_TYPE_MSB);
+        
+        inst->data.BranchData.BranchType = branchTypeFlag;
 
-    } else if (getBits(wrd, DATA_PROCESSING_DPREG_LSB, DATA_PROCESSING_DPREG_MSB) == 1) {
+        switch (branchTypeFlag) {
+            case a64inst_UNCONDITIONAL:
+                inst->data.BranchData.processOpData.unconditionalData.unconditionalOffset = getBits(wrd, BRANCH_UNCONDITIONAL_OFFSET_LSB, BRANCH_UNCONDITIONAL_OFFSET_MSB);
+                break;
+
+            case a64inst_CONDITIONAL:
+                inst->data.BranchData.processOpData.conditionalData.offset = getBits(wrd, BRANCH_CONDITIONAL_OFFSET_LSB, BRANCH_CONDITIONAL_OFFSET_MSB);
+                
+                word conditionFlag = getBits(wrd, BRANCH_CONDITIONAL_COND_LSB, BRANCH_CONDITIONAL_COND_MSB);
+
+                if(conditionFlag <= 1 || (conditionFlag >= 10 && conditionFlag <= 14)) {
+                    inst->data.BranchData.processOpData.conditionalData.cond = conditionFlag;
+                } else {
+                    fprintf(stderr, "Error: Unknown condition detected.\n");
+                    exit(1);
+                }
+                
+                break;
+
+            case a64inst_REGISTER:
+                inst->data.BranchData.processOpData.registerData.src = getBits(wrd, BRANCH_REGISTER_SRC_LSB, BRANCH_REGISTER_SRC_MSB);
+                break;
+
+            default:
+                fprintf(stderr, "Undefined branch type detected!\n");
+                exit(1);
+                break;
+        }
+
+    } else if (getBits(wrd, DATA_PROCESSING_REG_LSB, DATA_PROCESSING_REG_MSB) == 1) {
         inst->type = a64inst_DPREGISTER;
 
     } else {
diff --git a/src/decode.h b/src/decode.h
index 7eaa2fa..280d473 100644
--- a/src/decode.h
+++ b/src/decode.h
@@ -4,10 +4,21 @@
 #define BYTE_BITS 8
 #define HALT_WORD 0x8a000000
 
-#define DATA_PROCESSING_DPIMM_LSB 26
-#define DATA_PROCESSING_DPIMM_MSB 29
+#define DATA_PROCESSING_IMM_LSB 26
+#define DATA_PROCESSING_IMM_MSB 29
 
-#define DATA_PROCESSING_DPREG_LSB 25
-#define DATA_PROCESSING_DPREG_MSB 26
+#define DATA_PROCESSING_REG_LSB 25
+#define DATA_PROCESSING_REG_MSB 26
+
+#define BRANCH_TYPE_LSB 30
+#define BRANCH_TYPE_MSB 32
+#define BRANCH_UNCONDITIONAL_OFFSET_LSB 0
+#define BRANCH_UNCONDITIONAL_OFFSET_MSB 26
+#define BRANCH_REGISTER_SRC_LSB 5
+#define BRANCH_REGISTER_SRC_MSB 10
+#define BRANCH_CONDITIONAL_COND_LSB 0
+#define BRANCH_CONDITIONAL_COND_MSB 4
+#define BRANCH_CONDITIONAL_OFFSET_LSB 5
+#define BRANCH_CONDITIONAL_OFFSET_MSB 24
 
 a64inst_instruction *decode(word w);
\ No newline at end of file