From aaf052391d5243435b6bd4f23419105459438742 Mon Sep 17 00:00:00 2001
From: Danny Milosavljevic <dannym@scratchpost.org>
Date: Sat, 26 Dec 2020 16:39:31 +0100
Subject: [PATCH] arm-asm: Add nop

---
 arm-asm.c | 44 ++++++++++++++++++++++++++++++++++++++++++--
 arm-tok.h | 25 +++++++++++++++++++++++++
 2 files changed, 67 insertions(+), 2 deletions(-)

diff --git a/arm-asm.c b/arm-asm.c
index a15cd758..d4d4930e 100644
--- a/arm-asm.c
+++ b/arm-asm.c
@@ -31,6 +31,7 @@ ST_FUNC void gen_le32(int c);
 /*************************************************************/
 #else
 /*************************************************************/
+
 #define USING_GLOBALS
 #include "tcc.h"
 
@@ -64,9 +65,48 @@ ST_FUNC void gen_expr32(ExprValue *pe)
     gen_le32(pe->v);
 }
 
-ST_FUNC void asm_opcode(TCCState *s1, int opcode)
+static uint32_t condition_code_of_token(int token) {
+    if (token < TOK_ASM_nopeq) {
+        expect("instruction");
+        return 0;
+    } else
+        return (token - TOK_ASM_nopeq) & 15;
+}
+
+static void asm_emit_opcode(int token, uint32_t opcode) {
+    gen_le32((condition_code_of_token(token) << 28) | opcode);
+}
+
+static void asm_nullary_opcode(int token)
 {
-    tcc_error("internal error: asm_opcode not implemented");
+    switch (ARM_INSTRUCTION_GROUP(token)) {
+    case TOK_ASM_nopeq:
+        asm_emit_opcode(token, 0xd << 21); // mov r0, r0
+        break;
+    default:
+        expect("nullary instruction");
+    }
+}
+
+ST_FUNC void asm_opcode(TCCState *s1, int token)
+{
+    while (token == TOK_LINEFEED) {
+        next();
+        token = tok;
+    }
+    if (token == TOK_EOF)
+        return;
+    if (token < TOK_ASM_nopeq) {
+        expect("instruction");
+        return;
+    }
+
+    switch (ARM_INSTRUCTION_GROUP(token)) {
+    case TOK_ASM_nopeq:
+        return asm_nullary_opcode(token);
+    default:
+        expect("known instruction");
+    }
 }
 
 ST_FUNC void subst_asm_operand(CString *add_str, SValue *sv, int modifier)
diff --git a/arm-tok.h b/arm-tok.h
index 55232997..bcbabe3a 100644
--- a/arm-tok.h
+++ b/arm-tok.h
@@ -27,3 +27,28 @@
  DEF_ASM(sp) /* alias for r13 */
  DEF_ASM(lr) /* alias for r14 */
  DEF_ASM(pc) /* alias for r15 */
+
+#define ARM_INSTRUCTION_GROUP(tok) ((((tok) - TOK_ASM_nopeq) & 0xFFFFFFF0) + TOK_ASM_nopeq)
+
+/* Note: condition code is 4 bits */
+#define DEF_ASM_CONDED(x) \
+  DEF(TOK_ASM_ ## x ## eq, #x "eq") \
+  DEF(TOK_ASM_ ## x ## ne, #x "ne") \
+  DEF(TOK_ASM_ ## x ## cs, #x "cs") \
+  DEF(TOK_ASM_ ## x ## cc, #x "cc") \
+  DEF(TOK_ASM_ ## x ## mi, #x "mi") \
+  DEF(TOK_ASM_ ## x ## pl, #x "pl") \
+  DEF(TOK_ASM_ ## x ## vs, #x "vs") \
+  DEF(TOK_ASM_ ## x ## vc, #x "vc") \
+  DEF(TOK_ASM_ ## x ## hi, #x "hi") \
+  DEF(TOK_ASM_ ## x ## ls, #x "ls") \
+  DEF(TOK_ASM_ ## x ## ge, #x "ge") \
+  DEF(TOK_ASM_ ## x ## lt, #x "lt") \
+  DEF(TOK_ASM_ ## x ## gt, #x "gt") \
+  DEF(TOK_ASM_ ## x ## le, #x "le") \
+  DEF(TOK_ASM_ ## x, #x) \
+  DEF(TOK_ASM_ ## x ## rsvd, #x "rsvd")
+
+/* Note: add new tokens after nop (MUST always use DEF_ASM_CONDED) */
+
+ DEF_ASM_CONDED(nop)