From 074c293a045d2258d6f876868044a63f386c2b71 Mon Sep 17 00:00:00 2001
From: Nero <41307858+nero@users.noreply.github.com>
Date: Fri, 7 Jan 2022 22:06:03 +0000
Subject: [PATCH] Improve output format and add more encodings

---
 asm.awk | 51 ++++++++++++++++++++++++++-------------------------
 1 file changed, 26 insertions(+), 25 deletions(-)

diff --git a/asm.awk b/asm.awk
index 74b86c8..a53cf2e 100644
--- a/asm.awk
+++ b/asm.awk
@@ -97,12 +97,12 @@ BEGIN {
 # error string to insert into listing
 function err(str) {
   errors++
-  printf("ERR: %s:\n", str)
+  if (of=="lst") printf("**** %s:\n", str)
 }
 # submit a assembling result to output
 # set label of current line to off
 function submit(off) {
-  if (of=="lst") printf("%04X %-10s %s\n", off, hex, $0)
+  if (of=="lst") printf("%04X %-18s %s\n", off, hex, $0)
   if (of=="hex" && hex) printf("%s", hex)
   if (label) {
     if (of=="sym") printf("%s\tsym\t%d\n", label, off)
@@ -174,8 +174,8 @@ function modrm(str, spare, rs) {
 
 }
 # dont process empty lines or comment lines
-/^( |\t)*;/ || /^( |\t)*$/ {
-  if (of=="lst") printf("%16s%s\n","",$0)
+/^( |\t)*(;|%)/ || /^( |\t)*$/ {
+  if (of=="lst") printf("%24s%s\n","",$0)
   next
 }
 # load symbols from previous pass
@@ -273,39 +273,38 @@ op=="db" {
       for(j=2;j<length(a[i]);j++) {
         pushb(_ord_[substr(a[i],j,1)])
       }
-    } else {
-      pushb(getsym(a[i]))
-    }
+    } else pushb(getsym(a[i]))
   }
 }
 op=="dw" {
-  for(i=1;i<=c;i++) {
-    pushw(getsym(a[i]))
-  }
+  for(i=1;i<=c;i++) pushw(getsym(a[i]))
 }
-# x86 opcodes in approx. encoding order
+# x86 opcodes, ordered by my favourite first
 # arithmetics: ADD, SUB, XOR etc
 x86 && op in alu {
+  # modrm <- reg
   if (rm1 && op2 in r8) {
     pushb(0+alu[op]*8)
     modrm(op1, r8[op2], r8)
   } else if (rm1 && op2 in r16) {
     pushb(1+alu[op]*8)
     modrm(op1, r16[op2], r16)
+  # reg <- modrm
   } else if (op1 in r8 && rm2) {
     pushb(2+alu[op]*8)
     modrm(op2, r8[op1], r8)
   } else if (op1 in r16 && rm2) {
     pushb(3+alu[op]*8)
     modrm(op2, r16[op1], r16)
-  } else if (op1 in r16) {
-    pushb(129) # 81
-    modrm(op1, alu[op], r16)
-    pushw(getsym(op2))
-  } else if (op1 in r8) {
+  # modrm <- imm
+  } else if (byteop && rm1 || op1 in r8) {
     pushb(128) # 80
     modrm(op1, alu[op], r8)
     pushw(getsym(op2))
+  } else if (wordop && rm1 || op1 in r16) {
+    pushb(129) # 81
+    modrm(op1, alu[op], r16)
+    pushw(getsym(op2))
   }
 }
 # MOV variants
@@ -337,6 +336,13 @@ x86 && op=="mov" {
   } else if (op1 in r16) {
     pushb(184+r16[op1])
     pushw(getsym(op2))
+  # modrm <- imm
+  } else if (byteop && rm1) {
+    pushb(198)
+    modrm(rm1, 0, r16)
+  } else if (wordop && rm1) {
+    pushb(199)
+    modrm(rm1, 0, r16)
   }
 }
 x86 && op=="push" && op1 in r16 {
@@ -355,24 +361,19 @@ x86 && op=="int" { # CD
 }
 x86 && op=="jmp" {
   pushb(233)
-  v=getsym(op1)-(pos+3)
-  pushw(v)
+  pushw(getsym(op1)-(pos+3))
 }
 x86 && op=="call" {
   pushb(232)
-  v=getsym(op1)-(pos+3)
-  pushw(v)
+  pushw(getsym(op1)-(pos+3))
 }
 # opcodes with rel8 encoding
 x86 && op in ops_rel8 {
   pushb(ops_rel8[op])
-  v=getsym(op1)-(pos+2)
-  pushb(v)
+  pushb(getsym(op1)-(pos+2))
 }
 # opcodes without arguments
-x86 && op in ops_sb {
-  pushb(ops_sb[op])
-}
+x86 && op in ops_sb { pushb(ops_sb[op]) }
 {
   if (!hex) err("no encoding found")
   submit(pos)