From c827fdc960383130114116892741ed4853261452 Mon Sep 17 00:00:00 2001
From: Andrew Alderwick <andrew@alderwick.co.uk>
Date: Wed, 5 Jan 2022 01:27:27 +0000
Subject: [PATCH] Move errored stack identification to after error handling
 label.

Partial revert of commits 1ce8b9bc279468964deeb01ae6b4e9c15e52f625 (and
c296187ea9c950f544b8b69c8184b436f2743955).
---
 src/uxn.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/src/uxn.c b/src/uxn.c
index c3042af..4162f49 100644
--- a/src/uxn.c
+++ b/src/uxn.c
@@ -17,12 +17,11 @@ WITH REGARD TO THIS SOFTWARE.
 	pc: program counter. sp: ptr to src stack ptr. kptr: "keep" mode copy of src stack ptr.
 	x,y: macro in params. d: macro in device. j,k,dev: macro temp variables. o: macro out param. */
 
-#define FAULT(s, n) { errcode = n * 2 + (s == &u->rst); goto fault; }
-#define PUSH8(s, x) { if(s->ptr == 0xff) { FAULT(s, 2) } s->dat[s->ptr++] = (x); }
-#define PUSH16(s, x) { if((j = s->ptr) >= 0xfe) { FAULT(s, 2) } k = (x); s->dat[j] = k >> 8; s->dat[j + 1] = k; s->ptr = j + 2; }
+#define PUSH8(s, x) { if(s->ptr == 0xff) { errcode = 2; goto err; } s->dat[s->ptr++] = (x); }
+#define PUSH16(s, x) { if((j = s->ptr) >= 0xfe) { errcode = 2; goto err; } k = (x); s->dat[j] = k >> 8; s->dat[j + 1] = k; s->ptr = j + 2; }
 #define PUSH(s, x) { if(bs) { PUSH16(s, (x)) } else { PUSH8(s, (x)) } }
-#define POP8(o) { if(!(j = *sp)) { FAULT(src, 1) } o = (Uint16)src->dat[--j]; *sp = j; }
-#define POP16(o) { if((j = *sp) <= 1) { FAULT(src, 1) } o = src->dat[j - 1]; o += src->dat[j - 2] << 8; *sp = j - 2; }
+#define POP8(o) { if(!(j = *sp)) { errcode = 1; goto err; } o = (Uint16)src->dat[--j]; *sp = j; }
+#define POP16(o) { if((j = *sp) <= 1) { errcode = 1; goto err; } o = src->dat[j - 1]; o += src->dat[j - 2] << 8; *sp = j - 2; }
 #define POP(o) { if(bs) { POP16(o) } else { POP8(o) } }
 #define POKE(x, y) { if(bs) { u->ram[(x)] = (y) >> 8; u->ram[(x) + 1] = (y); } else { u->ram[(x)] = y; } }
 #define PEEK16(o, x) { o = (u->ram[(x)] << 8) + u->ram[(x) + 1]; }
@@ -90,7 +89,7 @@ uxn_eval(Uxn *u, Uint16 pc)
 		case 0x18: /* ADD */ POP(a) POP(b) PUSH(src, b + a) break;
 		case 0x19: /* SUB */ POP(a) POP(b) PUSH(src, b - a) break;
 		case 0x1a: /* MUL */ POP(a) POP(b) PUSH(src, (Uint32)b * a) break;
-		case 0x1b: /* DIV */ POP(a) POP(b) if(a == 0) { FAULT(src, 3) } PUSH(src, b / a) break;
+		case 0x1b: /* DIV */ POP(a) POP(b) if(a == 0) { errcode = 3; goto err; } PUSH(src, b / a) break;
 		case 0x1c: /* AND */ POP(a) POP(b) PUSH(src, b & a) break;
 		case 0x1d: /* ORA */ POP(a) POP(b) PUSH(src, b | a) break;
 		case 0x1e: /* EOR */ POP(a) POP(b) PUSH(src, b ^ a) break;
@@ -99,8 +98,11 @@ uxn_eval(Uxn *u, Uint16 pc)
 	}
 	return 1;
 
-fault:
-	return uxn_halt(u, errcode >> 1, (errcode & 1) == 0 ? "Working-stack" : "Return-stack", pc - 1);
+err:
+	if ((instr & 0x40 ? 1 : 0) ^ (errcode == 2 && ((instr & 0x1f) == 0x0e || (instr & 0x1f) == 0x0f)))
+		return uxn_halt(u, errcode, "Return-stack", pc - 1);
+	else
+		return uxn_halt(u, errcode, "Working-stack", pc - 1);
 }
 
 /* clang-format on */