From 458a1e662ad80cbef56487ebe75ee02358047944 Mon Sep 17 00:00:00 2001
From: Kimplul <kimi.h.kuparinen@gmail.com>
Date: Sat, 26 Aug 2023 18:38:30 +0300
Subject: allow specifying registers to run

---
 bcgen          | 41 +++++++++++++++++++++++++++++++----------
 example/main.c | 10 +++++++++-
 2 files changed, 40 insertions(+), 11 deletions(-)

diff --git a/bcgen b/bcgen
index 42e1f3f..6c0c574 100755
--- a/bcgen
+++ b/bcgen
@@ -36,7 +36,7 @@ struct compile_state {{
 
 {self.select_header}
 
-ubcval_t run(struct compile_state *cs);
+void run(struct compile_state *cs, ubcval_t ri[{self.r}], dbcval_t fi[{self.f}]);
 void init(struct compile_state *cs);
 void end(struct compile_state *cs);
 void destroy(struct compile_state *cs);
@@ -106,8 +106,13 @@ static void append(struct compile_state *cs, enum bcode_insn label,
 #define NEXT_INSN goto *s.op[++pc]
 #define JUMP(i) goto *s.op[pc = (i)]
 
-static ubcval_t _run(struct compile_state *cs, bool init)
+static void _run(struct compile_state *cs, bool init,
+    ubcval_t ri[{self.r}],
+    dbcval_t fi[{self.f}])
 {{
+        // silence warnings if zero registers defined
+        (void)ri;
+        (void)fi;
 	static void *labels[] = {{
 		[END] = &&end,
         {self.static}
@@ -115,7 +120,7 @@ static ubcval_t _run(struct compile_state *cs, bool init)
 
 	if (init) {{
 		cs->labels = labels;
-		return 0;
+		return;
 	}}
 
 {self.regs}
@@ -127,13 +132,14 @@ static ubcval_t _run(struct compile_state *cs, bool init)
 
 {self.body}
 
-end: /* we assume there's always at least one general register */
-	return r0;
+end:
+        {self.rregs}
+	return;
 }}
 
-ubcval_t run(struct compile_state *cs)
+void run(struct compile_state *cs, ubcval_t ri[{self.r}], dbcval_t fi[{self.f}])
 {{
-	return _run(cs, false);
+	_run(cs, false, ri, fi);
 }}
 
 void init(struct compile_state *cs)
@@ -150,7 +156,7 @@ void init(struct compile_state *cs)
 	assert(cs->s.op);
 
 	cs->pc = 0;
-	_run(cs, true);
+	_run(cs, true, NULL, NULL);
 }}
 
 void end(struct compile_state *cs)
@@ -274,6 +280,7 @@ class BCGen:
         self.regs = []
         self.body = []
         self.enum = []
+        self.rregs = []
         self.macro = []
         self.static = []
         self.select = []
@@ -398,8 +405,15 @@ class BCGen:
         self.gen_enum(name, fmt)
 
     def write(self, name='bcode'):
-        gregs = ['ubcval_t r' + str(i) + ' = 0;\n' for i in range(self.r)]
-        fregs = ['dbcval_t f' + str(i) + ' = 0;\n' for i in range(self.f)]
+        gregs = ['ubcval_t r' + str(i) + ' = ri[' + str(i) + '];\n'
+                    for i in range(self.r)]
+        fregs = ['dbcval_t f' + str(i) + ' = fi[' + str(i) + '];\n'
+                    for i in range(self.f)]
+
+        rgregs = ['ri[' + str(i) + '] = r' + str(i) + ';\n'
+                    for i in range(self.r)]
+        rfregs = ['fi[' + str(i) + '] = f' + str(i) +';\n'
+                    for i in range(self.f)]
 
         for g in gregs:
             self.regs += g
@@ -407,6 +421,12 @@ class BCGen:
         for f in fregs:
             self.regs += f
 
+        for g in rgregs:
+            self.rregs += g
+
+        for f in rfregs:
+            self.rregs += f
+
         with open(name + '.h', 'w') as f:
             self.select_header = ''.join(self.select_header)
             f.write(bcode_header_fmt.format(self=self))
@@ -422,6 +442,7 @@ class BCGen:
             self.regs = ''.join(self.regs)
             self.extra = ''.join(self.extra)
             self.body = ''.join(self.body)
+            self.rregs = ''.join(self.rregs)
 
             f.write(bcode_src_fmt.format(self=self))
 
diff --git a/example/main.c b/example/main.c
index dccec66..e9ab0a9 100644
--- a/example/main.c
+++ b/example/main.c
@@ -20,6 +20,14 @@ int main()
 
 	patch(&cs, r, 0, l);
 
-	printf("%llu\n", (unsigned long long)run(&cs));
+	/* specify register state to run, note that seven is taken from
+	 * r = 7 in rules.py, should probably provide a macro for it? */
+	ubcval_t ri[7] = {0};
+
+	/* since we don't use floating point registers, we can pass in a NULL */
+	run(&cs, ri, NULL);
+
+	/* our 'ABI' specifies that the return register is 0 */
+	printf("%llu\n", (unsigned long long)ri[0]);
 	destroy(&cs);
 }
-- 
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