1-3 complete

1-3/decoder.c

@@ -17,6 +17,48 @@
 /* 	CMP = 0b111, */
 /* } ARITHMETIC_OP; */
 
+typedef enum COND_JMP_OPC
+{
+	JX = 0b0111,
+	LOOPX = 0b1110'00,
+	
+} JMP_OPC;
+
+typedef enum LOOPX_INST
+{
+	LOOP   = 0b10,
+	LOOPZ  = 0b01,
+	LOOPNZ = 0b00,
+	JCXZ   = 0b11
+} LOOPX_INST;
+
+#define LOOPX_INST_TXT_LEN 7
+char LOOPX_INST_TXT[0b100][LOOPX_INST_TXT_LEN] = { "loopnz", "loopz", "loop", "jcxz" };
+
+typedef enum JX_INST
+{
+	JZ   = 0b0100,
+	JL   = 0b1100,
+	JLE   = 0b1110,
+	JB   = 0b0010,
+	JBE   = 0b0110,
+	JP   = 0b1010,
+	JO   = 0b0000,
+	JS   = 0b1000,
+	JNE  = 0b0101,
+	JNL  = 0b1101,
+	JNLE  = 0b1111,
+	JNB  = 0b0011,
+	JNBE  = 0b0111,
+	JNP  = 0b1011,
+	JNO = 0b0001,
+	JNS = 0b1001,
+} JX_INST;
+
+#define JX_INST_TXT_LEN 5
+char JX_INST_TXT[0b10000][JX_INST_TXT_LEN] = { "jo", "jno", "jb", "jnb", "jz", "jne", "jbe", "jnbe",
+                                               "js", "jns", "jp", "jnp", "jl", "jnl", "jle", "jnle" };
+
 typedef enum ARITHMETIC_OP
 {
 	ADD = 0b000,
@@ -351,7 +393,7 @@ int16_t calc_effective_disp(uint8_t high_order, uint8_t low_order, bool lo_only)
 	const uint8_t low_order_neg_mask = 0b1000'0000;
     int16_t effective_disp = 0;
 
-	if (lo_only & ((low_order & low_order_neg_mask) >> 7))
+	if (lo_only && ((low_order & low_order_neg_mask) >> 7))
 		high_order = high_order | 0b1111'1111;
 	int8_t *effective_disp_high_order =(int8_t*) &(effective_disp) + 1;
 	memcpy(&(effective_disp), &low_order, 1);
@@ -682,14 +724,14 @@ int ASC_I_RM_parse(uint8_t byte1, uint8_t byte2, binary_data *binary, int bytes_
 		effective_disp = calc_effective_disp(high_disp, low_disp, false);
 
 		low_data = payload[2];		
-		if (is_wide)
+		if (is_wide && !is_sign)
 		{	
 			high_data = payload[3];
 			effective_data = calc_effective_disp(high_data, low_data, false);
 		}
 		else
 		{
-			effective_data = calc_effective_disp(0, low_disp, true);	
+			effective_data = calc_effective_disp(0, low_data, true);	
 		}
 
 		fill_ea_string(&mem_data, EA_ENCODING_TXT[ea_table_value], effective_disp);
@@ -828,6 +870,23 @@ int ASC_REGM_R_parse(uint8_t byte1, uint8_t byte2, binary_data *binary, int byte
 	return extra_bytes_read;
 }
 
+void JMP_parse(uint8_t byte1, uint8_t byte2, binary_data *binary, int bytes_read, JMP_OPC op)
+{
+	const uint8_t loopx_mask = 0b0000'0011;
+	const uint8_t jx_mask  = 0b0000'1111; 	
+    int8_t disp = 0;
+	memcpy(&disp, &byte2, sizeof(uint8_t));
+	uint8_t jump_op = (op == LOOPX) ? (byte1 & loopx_mask) : (byte1 & jx_mask);
+
+	char nasm_offset[4] = { "\0" };
+	if (!disp) strcpy(nasm_offset, "$+");
+	else       strcpy(nasm_offset, "$+2");
+
+	//We have to add +2 to displacement so that NASM can parse displacements correctly
+	printf("%s %s%+d \n", (op == LOOPX) ? LOOPX_INST_TXT[jump_op] : JX_INST_TXT[jump_op], nasm_offset, disp);
+	fprintf(output, "%s %s%+d \n", (op == LOOPX) ? LOOPX_INST_TXT[jump_op] : JX_INST_TXT[jump_op], nasm_offset, disp);
+}
+
 int main(int argc, char** argv)
 {
 	if (argc != 2) return -1;
@@ -848,8 +907,9 @@ int main(int argc, char** argv)
 		fread(byte, sizeof(byte), 1, bin.binary);
 		uint8_t manip_inst = (uint8_t)byte[0];
 		uint8_t inst = (uint8_t)byte[0];
-		//First, we check for ASC. 
+		//First, we check for ASC or JMPs. 
 		manip_inst = (manip_inst >> 1);
+		
 		if ((manip_inst & ASC_I_A_M) == ASC_I_A)
 		{
 			if (bytes_read >= bin.size) break;
@@ -860,6 +920,15 @@ int main(int argc, char** argv)
 			continue;
 		}
 		manip_inst = (inst >> 2);
+		if (manip_inst == LOOPX)
+		{
+            if (bytes_read >= bin.size) break; 
+    	    fread(byte, sizeof(byte), 1, bin.binary);
+			bytes_read++;
+			inst_byte2 = (uint8_t)byte[0];
+    		JMP_parse(inst, inst_byte2, 0, 0, LOOPX);
+			continue;
+		}
 		if ((manip_inst & ASC_REGM_R_M) == ASC_REGM_R)
 		{
 			if (bytes_read >= bin.size) break;
@@ -878,6 +947,16 @@ int main(int argc, char** argv)
     		bytes_read += ASC_I_RM_parse(inst, inst_byte2, 0, 0);
 			continue;
 		}
+		manip_inst = (inst >> 4);
+		if (manip_inst == JX)
+		{
+            if (bytes_read >= bin.size) break; 
+    	    fread(byte, sizeof(byte), 1, bin.binary);
+			bytes_read++;
+			inst_byte2 = (uint8_t)byte[0];
+    		JMP_parse(inst, inst_byte2, 0, 0, JX);
+			continue;
+		}
 		//Then, we're checking for all MOV except segment registers
 		manip_inst = (inst >> 1);
 		switch (manip_inst)

1-3/listing-41.asm

@@ -1,26 +1,10 @@
-; ========================================================================
+;bits 16
 ;
-; (C) Copyright 2023 by Molly Rocket, Inc., All Rights Reserved.
-;
-; This software is provided 'as-is', without any express or implied
-; warranty. In no event will the authors be held liable for any damages
-; arising from the use of this software.
-;
-; Please see https://computerenhance.com for further information
-;
-; ========================================================================
-
-; ========================================================================
-; LISTING 41
-; ========================================================================
-
-bits 16
-
 ;add bx, [bx+si]
 ;add bx, [bp]
-add si, 2						
+;add si, 2						
-add bp, 2
+;add bp, 2
-add cx, 8
+;add cx, 8
 ;add bx, [bp + 0]
 ;add cx, [bx + 2]
 ;add bh, [bp + si + 4]
@@ -31,21 +15,20 @@ add cx, 8
 ;add [bx + 2], cx
 ;add [bp + si + 4], bh
 ;add [bp + di + 6], di
-add byte [bx], 34
+;add byte [bx], 34
-add word [bp + si + 1000], 29
+;add word [bp + si + 1000], 29
 ;add ax, [bp]
 ;add al, [bx + si]
 ;add ax, bx
-add al, ah
+;add al, ah
-add ax, 1000 
+;add ax, 1000 
-add al, -30
+;add al, -30
-add al, 9
+;add al, 9
-
 ;sub bx, [bx+si]
 ;sub bx, [bp]
-sub si, 2
+;sub si, 2
-sub bp, 2
+;sub bp, 2
-sub cx, 8
+;sub cx, 8
 ;sub bx, [bp + 0]
 ;sub cx, [bx + 2]
 ;sub bh, [bp + si + 4]
@@ -56,21 +39,20 @@ sub cx, 8
 ;sub [bx + 2], cx
 ;sub [bp + si + 4], bh
 ;sub [bp + di + 6], di
-sub byte [bx], 34
+;sub byte [bx], 34
-sub word [bx + di], 29
+;sub word [bx + di], 29
 ;sub ax, [bp]
 ;sub al, [bx + si]
 ;sub ax, bx
 ;sub al, ah
-sub ax, 1000
+;sub ax, 1000
-sub al, -30
+;sub al, -30
-sub al, 9
+;sub al, 9
-
 ;cmp bx, [bx+si]
 ;cmp bx, [bp]
-cmp si, 2
+;cmp si, 2
-cmp bp, 2
+;cmp bp, 2
-cmp cx, 8
+;cmp cx, 8
 ;cmp bx, [bp + 0]
 ;cmp cx, [bx + 2]
 ;cmp bh, [bp + si + 4]
@@ -81,41 +63,41 @@ cmp cx, 8
 ;cmp [bx + 2], cx
 ;cmp [bp + si + 4], bh
 ;cmp [bp + di + 6], di
-cmp byte [bx], 34
+;cmp byte [bx], 34
-cmp word [4834], 29
+;cmp word [4834], 29
 ;cmp ax, [bp]
 ;cmp al, [bx + si]
 ;cmp ax, bx
 ;cmp al, ah
-cmp ax, 1000
+;cmp ax, 1000
-cmp al, -30
+;cmp al, -30
-cmp al, 9
+;cmp al, 9
 
-; test_label0:
+test_label0:
-; jnz test_label1
+jnz test_label1
-; jnz test_label0
+jnz test_label0
-; test_label1:
+test_label1:
-; jnz test_label0
+jnz test_label0
-; jnz test_label1
+jnz test_label1
-; 
+	
-; label:
+label:
-; je label
+je label
-; jl label
+jl label
-; jle label
+jle label
-; jb label
+jb label
-; jbe label
+jbe label
-; jp label
+jp label
-; jo label
+jo label
-; js label
+js label
-; jne label
+jne label
-; jnl label
+jnl label
-; jg label
+jg label
-; jnb label
+jnb label
-; ja label
+ja label
-; jnp label
+jnp label
-; jno label
+jno label
-; jns label
+jns label
-; loop label
+loop label
-; loopz label
+loopz label
-; loopnz label
+loopnz label
-; jcxz label
+jcxz label

1-3/output.asm

@@ -0,0 +1,26 @@
+bits 16
+
+jne $+2+2 
+jne $+2-4 
+jne $+2-6 
+jne $+2-4 
+jz $+2-2 
+jl $+2-4 
+jle $+2-6 
+jb $+2-8 
+jbe $+2-10 
+jp $+2-12 
+jo $+2-14 
+js $+2-16 
+jne $+2-18 
+jnl $+2-20 
+jnle $+2-22 
+jnb $+2-24 
+jnbe $+2-26 
+jnp $+2-28 
+jno $+2-30 
+jns $+2-32 
+loop $+2-34 
+loopz $+2-36 
+loopnz $+2-38 
+jcxz $+2-40