From 04cbdbcbf07c340c2e6a4e77d726e925eb6f2801 Mon Sep 17 00:00:00 2001
From: obones <obones@free.fr>
Date: Fri, 12 Nov 2021 17:34:43 +0100
Subject: [PATCH] Add RTL_433_REDUCE_STACK_USE to reduce size of bitbuffers
 (#1863)

- introduce RTL_433_REDUCE_STACK_USE which, when defined, drastically reduces the size of bitrow_t, thus saving lots of stack space.
---
 include/bitbuffer.h             |  6 ++++++
 src/devices/lacrossews.c        |  2 +-
 src/devices/oregon_scientific.c | 11 +++++++----
 3 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/include/bitbuffer.h b/include/bitbuffer.h
index 867f758e..a08f4bdd 100644
--- a/include/bitbuffer.h
+++ b/include/bitbuffer.h
@@ -15,8 +15,14 @@
 #include <stdint.h>
 
 // NOTE: Wireless mbus protocol needs at least ((256+16*2+3)*12)/8 => 437 bytes
+//       which fits even if RTL_433_REDUCE_STACK_USE is defined because of row spilling
+#ifdef RTL_433_REDUCE_STACK_USE
+#define BITBUF_COLS 40 // Number of bytes in a column
+#define BITBUF_ROWS 25
+#else
 #define BITBUF_COLS 128 // Number of bytes in a column
 #define BITBUF_ROWS 50
+#endif
 #define BITBUF_MAX_PRINT_BITS 50 // Maximum number of bits to print (in addition to hex values)
 
 typedef uint8_t bitrow_t[BITBUF_COLS];
diff --git a/src/devices/lacrossews.c b/src/devices/lacrossews.c
index 344ff510..3f4117fc 100644
--- a/src/devices/lacrossews.c
+++ b/src/devices/lacrossews.c
@@ -100,7 +100,7 @@ static int lacrossews_callback(r_device *decoder, bitbuffer_t *bitbuffer)
     float temp_c, wind_dir, wind_spd, rain_mm;
     data_t *data;
 
-    for (row = 0; row < BITBUF_ROWS; row++) {
+    for (row = 0; row < bitbuffer->num_rows; row++) {
         // break out the message nybbles into separate bytes
         if (lacrossews_detect(decoder, bitbuffer->bb[row], msg_nybbles, bitbuffer->bits_per_row[row]) <= 0)
             continue; // DECODE_ABORT_EARLY
diff --git a/src/devices/oregon_scientific.c b/src/devices/oregon_scientific.c
index 0cc277ca..d8f83eb1 100644
--- a/src/devices/oregon_scientific.c
+++ b/src/devices/oregon_scientific.c
@@ -568,6 +568,9 @@ static int oregon_scientific_v2_1_decode(r_device *decoder, bitbuffer_t *bitbuff
     return 0;
 }
 
+// ceil( (335 + 11) / 8 )
+#define EXPECTED_NUM_BYTES 44
+
 static int oregon_scientific_v3_decode(r_device *decoder, bitbuffer_t *bitbuffer)
 {
     uint8_t *b = bitbuffer->bb[0];
@@ -583,7 +586,7 @@ static int oregon_scientific_v3_decode(r_device *decoder, bitbuffer_t *bitbuffer
         return DECODE_ABORT_EARLY;
     }
 
-    unsigned char msg[BITBUF_COLS] = {0};
+    unsigned char msg[EXPECTED_NUM_BYTES] = {0};
     int msg_pos = 0;
     int msg_len = 0;
 
@@ -627,7 +630,7 @@ static int oregon_scientific_v3_decode(r_device *decoder, bitbuffer_t *bitbuffer
         msg_len = bitbuffer->bits_per_row[0] - alt_pos;
     }
 
-    if (msg_len == 0)
+    if (msg_len == 0 || msg_len > (int)sizeof(msg) * 8)
         return DECODE_ABORT_EARLY;
 
     bitbuffer_extract_bytes(bitbuffer, 0, msg_pos, msg, msg_len);
@@ -759,7 +762,7 @@ static int oregon_scientific_v3_decode(r_device *decoder, bitbuffer_t *bitbuffer
     else if (msg[0] == 0x26) { // Owl CM180 readings
         msg[0]    = msg[0] & 0x0f;
         int valid = validate_os_checksum(decoder, msg, 23);
-        for (int k = 0; k < BITBUF_COLS; k++) { // Reverse nibbles
+        for (int k = 0; k < EXPECTED_NUM_BYTES; k++) { // Reverse nibbles
             msg[k] = (msg[k] & 0xF0) >> 4 | (msg[k] & 0x0F) << 4;
         }
         // TODO: should we return if valid == 0?
@@ -791,7 +794,7 @@ static int oregon_scientific_v3_decode(r_device *decoder, bitbuffer_t *bitbuffer
         msg[0]    = msg[0] & 0x0f;
         // to be done
         // int valid = validate_os_checksum(decoder, msg, 23);
-        for (int k = 0; k < BITBUF_COLS; k++) { // Reverse nibbles
+        for (int k = 0; k < EXPECTED_NUM_BYTES; k++) { // Reverse nibbles
             msg[k] = (msg[k] & 0xF0) >> 4 | (msg[k] & 0x0F) << 4;
         }
         // TODO: should we return if valid == 0?