From d3879906fb63fdeab9d28f651d2242eade251402 Mon Sep 17 00:00:00 2001
From: mrb0nk500 <b0nk@b0nk.xyz>
Date: Wed, 13 Nov 2019 12:06:03 -0500
Subject: Actually set the Processor Status flags correctly, and revamp some
 other stuff.

---
 sux.c | 77 ++++++++++++++++++++++++++++++++++++++++++++++---------------------
 1 file changed, 53 insertions(+), 24 deletions(-)

(limited to 'sux.c')

diff --git a/sux.c b/sux.c
index 1efbc77..de32a14 100644
--- a/sux.c
+++ b/sux.c
@@ -7,37 +7,54 @@ uint8_t crt; /* Current Running Threads. */
 uint64_t pc[8]; /* Program counter. */
 uint64_t ps; /* Processor status. */
 
+uint64_t rol(uint64_t a, uint64_t value) {
+	const uint64_t mask = 8 * sizeof(a) - 1;
+	value &= mask;
+	return (a << value) | (a >> (-value & mask));
+}
+
+uint64_t ror(uint64_t a, uint64_t value) {
+	const uint64_t mask = 8 * sizeof(a) - 1;
+	value &= mask;
+	return (a >> value) | (a << (-value & mask));
+}
+
 int alu(uint8_t opcode, uint64_t value) {
 	uint64_t sum;
-	uint8_t carry = 0, vf = 0;
+	uint8_t c = 0; /* Carry flag. */
+	uint8_t v = 0; /* Overflow flag. */
+	uint8_t z = 0; /* Zero flag. */
+	uint8_t n = 0; /* Negative flag. */
 	switch(opcode) {
 		/* Add with carry. */
 		case ADC:
-			sum = a+value+carry;
-			vf = (~(a^value) & (a^sum & 0x80));
-			carry = (sum < value) ? 1 : 0;
-			a |= sum;
+			c = ps & 1;
+			sum = a+value+c;
+			v = !((a^value) & 0x8000000000000000) && ((a^sum) & 0x8000000000000000);
+			c = (sum < value);
+			a = sum;
 			break;
 		/* Subtract with carry. */
 		case SBC:
-			sum = a-value-!carry;
-			vf = (a^value) & (a^sum) & 0x80;
-			carry = (sum > value) ? 1 : 0;
-			a |= sum;
+			c = !(ps & 1);
+			sum = a-value-c;
+			v = ((a^value) & 0x8000000000000000) && ((a^sum) & 0x8000000000000000);
+			c = (sum > value);
+			a = sum;
 			break;
 		/* Multiply with accumulator. */
 		case MUL:
-			sum = a*value+carry;
-			vf = (~(a^value) & (a^sum & 0x80));
-			carry = (sum < value) ? 1 : 0;
-			a |= sum;
+			c = ps & 1;
+			sum = a*value+c;
+			v = !((a^value) & 0x8000000000000000) && ((a^sum) & 0x8000000000000000);
+			c = (!((a^sum) && (a^value)) || (a >= ((uint64_t)1 << 32) && value >= ((uint64_t)1 << 32)));
+			a = sum;
 			break;
 		/* Divide with accumulator. */
 		case DIV:
-			sum = a/value-!carry;
-			vf = (a^value) & (a^sum) & 0x80;
-			carry = (sum > value) ? 1 : 0;
-			a |= sum;
+			sum = a/value;
+			v = ((a^value) & 0x8000000000000000) && ((a^sum) & 0x8000000000000000);
+			a = sum;
 			break;
 		/* Bitwise AND. */
 		case AND:
@@ -89,23 +106,31 @@ int alu(uint8_t opcode, uint64_t value) {
 			break;
 		/* Shift accumulator left. */
 		case SLA:
-			a <<= value;
+			sum = (value < 64) ? a << value : 0;
+			c = (sum < a << value && value >= 64);
+			a = sum;
 			break;
 		/* Shift accumulator right. */
 		case SRA:
-			a >>= value;
+			sum = (value < 64) ? a << value : 0;
+			c = (sum < a >> value && value >= 64);
+			a = sum;
 			break;
 		/* Rotate accumulator left. */
 		case ROL:
-			(a << value) | (a >> (64-value));
+			a = rol(a, value);
 			break;
 		/* Rotate accumulator right. */
 		case ROR:
-			(a >> value) | (a << (64-value));
+			a = ror(a, value);
 			break;
 	}
-	ps |= vf;
-	ps |= carry;
+	z = (a == 0);
+	n = (a >> 63);
+	ps = (n) ? (ps | 1 << 7) : (ps & 1 << 7);
+	ps = (v) ? (ps | 1 << 6) : (ps & 1 << 6);
+	ps = (z) ? (ps | 1 << 1) : (ps & 1 << 1);
+	ps = (c) ? (ps | 1 << 0) : (ps & 1 << 0);
 	return 1;
 }
 
@@ -142,8 +167,12 @@ int branch(uint8_t opcode, uint64_t value, uint8_t thread) {
 					break;
 				/* Return from subroutine. */
 				case RTS:
-					pulladdr();
+					pc[thread] = pulladdr();
 					break;
 			}
 	}
 }
+
+int memory(uint8_t opcode, uint64_t value) {
+
+}
-- 
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