[common] lgmp: separate transport configuration

Move LGMP queue tunables into LGMPConfig.h and keep compatibility
aliases in KVMFR.h. Promote color-transform, SDR white-level, and
damage-limit definitions to transport-neutral common types so non-LGMP
transports do not depend on the KVMFR wire format.

common/include/common/KVMFR.h

@@ -26,22 +26,16 @@
 #include <stdint.h>
 #include <stdbool.h>
 #include "types.h"
+#include "LGMPConfig.h"
 
 #define KVMFR_MAGIC   "KVMFR---"
 #define KVMFR_VERSION 23
 
 // Fallback used by producers that cannot report the source display's SDR
 // white level. IDD frames override this with IDDCX_METADATA2::SdrWhiteLevel.
-#define KVMFR_SDR_WHITE_LEVEL_DEFAULT 203
-
-#define KVMFR_MAX_DAMAGE_RECTS 64
-
-#define LGMP_Q_POINTER     1
-#define LGMP_Q_FRAME       2
-
-#define LGMP_Q_FRAME_LEN   2
-#define LGMP_Q_POINTER_LEN 32
+#define KVMFR_SDR_WHITE_LEVEL_DEFAULT LG_SDR_WHITE_LEVEL_DEFAULT
 
+#define KVMFR_MAX_DAMAGE_RECTS LG_MAX_FRAME_DAMAGE_RECTS
 
 #ifdef _MSC_VER
  // don't warn on zero length arrays
@@ -144,25 +138,18 @@ KVMFRCursor;
 
 enum
 {
-  KVMFR_COLOR_TRANSFORM_MATRIX = 0x1,
-  KVMFR_COLOR_TRANSFORM_LUT    = 0x2,
+  KVMFR_COLOR_TRANSFORM_MATRIX = LG_COLOR_TRANSFORM_MATRIX,
+  KVMFR_COLOR_TRANSFORM_LUT    = LG_COLOR_TRANSFORM_LUT,
 };
 
-typedef uint32_t KVMFRColorTransformFlags;
+typedef LGColorTransformFlags KVMFRColorTransformFlags;
 
 // Optional payload appended to KVMFRCursor when
 // CURSOR_FLAG_COLOR_TRANSFORM is present. The matrix is an XYZ-to-XYZ
 // adjustment; the LUT is applied after encoding to the active wire transfer
 // function. Four LUT components keep the payload directly uploadable as an
 // RGBA32F texture, with alpha reserved and set to 1.0.
-typedef struct KVMFRColorTransform
-{
-  KVMFRColorTransformFlags flags;
-  float matrix[3][4];
-  float scalar;
-  float lut[4096][4];
-}
-KVMFRColorTransform;
+typedef LGColorTransform KVMFRColorTransform;
 
 enum
 {

common/include/common/LGMPConfig.h

@@ -0,0 +1,30 @@
+/**
+ * Looking Glass
+ * Copyright © 2017-2026 The Looking Glass Authors
+ * https://looking-glass.io
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc., 59
+ * Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#ifndef _H_LG_COMMON_LGMP_CONFIG_
+#define _H_LG_COMMON_LGMP_CONFIG_
+
+#define LGMP_Q_POINTER     1
+#define LGMP_Q_FRAME       2
+
+#define LGMP_Q_FRAME_LEN   2
+#define LGMP_Q_POINTER_LEN 32
+
+#endif

common/include/common/stringutils.h

@@ -22,6 +22,7 @@
 #define _H_LG_COMMON_STRINGUTILS
 
 #include <stdbool.h>
+#include <stddef.h>
 
 // vsprintf but with buffer allocation
 int valloc_sprintf(char ** str, const char * format, va_list ap)
@@ -37,6 +38,9 @@ bool str_containsValue(const char * list, char delimiter, const char * value);
 // Local implementation of strdup
 char * lg_strdup(const char *s);
 
+// copy a potentially unterminated string into a null-terminated buffer
+void str_copy(char * dst, size_t dstSize, const char * src, size_t srcSize);
+
 // search a non null terminated buffer for a value
 const char * memsearch(
     const char * haystack, size_t haystackSize,

common/include/common/types.h

@@ -89,6 +89,26 @@ typedef enum CursorType
 }
 CursorType;
 
+enum
+{
+  LG_COLOR_TRANSFORM_MATRIX = 0x1,
+  LG_COLOR_TRANSFORM_LUT    = 0x2,
+};
+
+typedef uint32_t LGColorTransformFlags;
+
+#define LG_SDR_WHITE_LEVEL_DEFAULT 203
+#define LG_MAX_FRAME_DAMAGE_RECTS  64
+
+typedef struct LGColorTransform
+{
+  LGColorTransformFlags flags;
+  float matrix[3][4];
+  float scalar;
+  float lut[4096][4];
+}
+LGColorTransform;
+
 typedef struct StringPair
 {
   const char * name;

common/src/stringutils.c

@@ -112,6 +112,20 @@ char * lg_strdup(const char *s)
   return out;
 }
 
+void str_copy(char * dst, size_t dstSize, const char * src, size_t srcSize)
+{
+  if (!dstSize)
+    return;
+
+  const char * end       = memchr(src, 0, srcSize);
+  const size_t srcLength = end ? (size_t)(end - src) : srcSize;
+  const size_t copySize  = srcLength < dstSize - 1 ?
+    srcLength : dstSize - 1;
+
+  memcpy(dst, src, copySize);
+  dst[copySize] = 0;
+}
+
 const char * memsearch(
     const char * haystack, size_t haystackSize,
     const char * needle  , size_t needleSize  ,