From de9f70375c1967c9d24f9181b66bbb949afee47f Mon Sep 17 00:00:00 2001
From: Jakob Gruber <jakob.gruber@gmail.com>
Date: Wed, 18 Jul 2012 12:37:50 +0200
Subject: [PATCH] gdb: Read/write SREG values correctly

Accessing SREG through gdb seems to have been broken since SREG is no
longer synthesized at each instruction (2f67001d). As a quick fix, make
SREG accessors public and use them in sim_gdb.

Note that invalid avr->sreg values no longer trigger the CRASH macro.
---
 simavr/sim/sim_core.c | 11 ++---------
 simavr/sim/sim_core.h | 20 ++++++++++++++++++++
 simavr/sim/sim_gdb.c  |  9 +++++++--
 3 files changed, 29 insertions(+), 11 deletions(-)

diff --git a/simavr/sim/sim_core.c b/simavr/sim/sim_core.c
index f3106ef..33073c8 100644
--- a/simavr/sim/sim_core.c
+++ b/simavr/sim/sim_core.c
@@ -155,8 +155,7 @@ static inline void _avr_set_r(avr_t * avr, uint8_t r, uint8_t v)
 	if (r == R_SREG) {
 		avr->data[R_SREG] = v;
 		// unsplit the SREG
-		for (int i = 0; i < 8; i++)
-			avr->sreg[i] = (v & (1 << i)) != 0;
+		SET_SREG_FROM(avr, v);
 		SREG();
 	}
 	if (r > 31) {
@@ -209,13 +208,7 @@ static inline uint8_t _avr_get_ram(avr_t * avr, uint16_t addr)
 		 * SREG is special it's reconstructed when read
 		 * while the core itself uses the "shortcut" array
 		 */
-		avr->data[R_SREG] = 0;
-		for (int i = 0; i < 8; i++)
-			if (avr->sreg[i] > 1) {
-				printf("** Invalid SREG!!\n");
-				CRASH();
-			} else if (avr->sreg[i])
-				avr->data[R_SREG] |= (1 << i);
+		READ_SREG_INTO(avr, avr->data[R_SREG]);
 		
 	} else if (addr > 31 && addr < 256) {
 		uint8_t io = AVR_DATA_TO_IO(addr);
diff --git a/simavr/sim/sim_core.h b/simavr/sim/sim_core.h
index 9f83654..a3a4c28 100644
--- a/simavr/sim/sim_core.h
+++ b/simavr/sim/sim_core.h
@@ -95,6 +95,26 @@ void avr_dump_state(avr_t * avr);
 
 #endif 
 
+/**
+ * Reconstructs the SREG value from avr->sreg into dst.
+ */
+#define READ_SREG_INTO(avr, dst) { \
+			dst = 0; \
+			for (int i = 0; i < 8; i++) \
+				if (avr->sreg[i] > 1) { \
+					printf("** Invalid SREG!!\n"); \
+				} else if (avr->sreg[i]) \
+					dst |= (1 << i); \
+		}
+
+/**
+ * Splits the SREG value from src into the avr->sreg array.
+ */
+#define SET_SREG_FROM(avr, src) { \
+			for (int i = 0; i < 8; i++) \
+				avr->sreg[i] = (src & (1 << i)) != 0; \
+		}
+
 #ifdef __cplusplus
 };
 #endif
diff --git a/simavr/sim/sim_gdb.c b/simavr/sim/sim_gdb.c
index d5313fd..ac6d068 100644
--- a/simavr/sim/sim_gdb.c
+++ b/simavr/sim/sim_gdb.c
@@ -32,6 +32,7 @@
 #include <poll.h>
 #include <pthread.h>
 #include "sim_avr.h"
+#include "sim_core.h" // for SET_SREG_FROM, READ_SREG_INTO
 #include "sim_hex.h"
 #include "avr_eeprom.h"
 #include "sim_gdb.h"
@@ -210,6 +211,7 @@ static int gdb_write_register(avr_gdb_t * g, int regi, uint8_t * src)
 			return 1;
 		case 32:
 			g->avr->data[R_SREG] = *src;
+			SET_SREG_FROM(g->avr, *src);
 			return 1;
 		case 33:
 			g->avr->data[R_SPL] = src[0];
@@ -228,8 +230,11 @@ static int gdb_read_register(avr_gdb_t * g, int regi, char * rep)
 		case 0 ... 31:
 			sprintf(rep, "%02x", g->avr->data[regi]);
 			break;
-		case 32:
-			sprintf(rep, "%02x", g->avr->data[R_SREG]);
+		case 32: {
+				uint8_t sreg;
+				READ_SREG_INTO(g->avr, sreg);
+				sprintf(rep, "%02x", sreg);
+			}
 			break;
 		case 33:
 			sprintf(rep, "%02x%02x", g->avr->data[R_SPL], g->avr->data[R_SPH]);
-- 
2.39.5