From 7c247d718149334554fb02a1e444e48d2c7fcecf Mon Sep 17 00:00:00 2001
From: Devine Lu Linvega <aliceffekt@gmail.com>
Date: Sat, 4 May 2024 12:34:38 -0700
Subject: [PATCH] Smarter clean up of dirty registers

---
 src/modal.c | 20 ++++++--------------
 1 file changed, 6 insertions(+), 14 deletions(-)

diff --git a/src/modal.c b/src/modal.c
index 66c0dfb..f14f906 100644
--- a/src/modal.c
+++ b/src/modal.c
@@ -5,13 +5,12 @@ typedef struct {
 	char *a, *b;
 } Rule;
 
-static unsigned char rmin = 0xff, rmax = 0x00;
 static int flip, quiet, debug, cycles = 0x10000;
 static Rule rules[0x1000], *rules_ = rules, lambda;
 static char dict[0x8000], *dict_ = dict, empty;
 static char bank_a[0x4000], *src_ = bank_a;
 static char bank_b[0x4000], *dst_ = bank_b;
-static char *regs[0x100];
+static char *regs[0x100], stack[0x10], *stack_ = stack;
 
 #define spacer(c) (c <= ' ' || c == '(' || c == ')')
 
@@ -148,14 +147,10 @@ write_tail(char *s)
 static int
 apply_rule(Rule *r, char *s)
 {
-	unsigned char i, rid;
+	unsigned char rid;
 	char c, *a = r->a, *b = r->b, *origin = dst_, *reg;
 	/* phase: clean regs */
-	if(rmax) {
-		for(i = 0; i <= rmax; i++)
-			regs[i] = 0;
-		rmin = 0xff, rmax = 0x00;
-	}
+	while(stack_ != stack) regs[(int)*(--stack_)] = 0;
 	/* phase: match rule */
 	while((c = *a++)) {
 		if(c == '?') {
@@ -165,11 +160,8 @@ apply_rule(Rule *r, char *s)
 				char *rcap = walk(reg), *pp = s;
 				while(reg < rcap || pp < pcap)
 					if(*reg++ != *pp++) return 0;
-			} else { /* reg set */
-				regs[rid] = s;
-				if(rid < rmin) rmin = rid;
-				if(rid > rmax) rmax = rid;
-			}
+			} else /* reg set */
+				regs[rid] = s, *stack_++ = rid;
 			s = pcap;
 		} else if(c != *s++)
 			return 0;
@@ -294,7 +286,7 @@ main(int argc, char **argv)
 		return !printf("usage: modal [-vqn] source.modal\n");
 	for(i = 1; i < argc && *argv[i] == '-'; i++) {
 		switch(argv[i][1]) {
-		case 'v': /* version */ return !printf("Modal Interpreter, 2 May 2024.\n");
+		case 'v': /* version */ return !printf("Modal Interpreter, 4 May 2024.\n");
 		case 'q': /* quiet */ quiet = 1; break;
 		case 'p': /* debug */ debug = 1; break;
 		case 'n': /* infinite */ cycles = 0xffffffff; break;