build: enable strict aliasing optimisations

[xonotic/darkplaces.git] / com_msg.c

diff --git a/com_msg.c b/com_msg.c
index 0c4542bb467772bb4fce7950b0474f4495af6667..80503b62b5307ff3d1ebf44ebf94da2aa02144e4 100644 (file)
--- a/com_msg.c
+++ b/com_msg.c
@@ -1,5 +1,6 @@
 /*
 Copyright (C) 1996-1997 Id Software, Inc.
+Copyright (C) 2000-2020 DarkPlaces contributors
 
 This program is free software; you can redistribute it and/or
 modify it under the terms of the GNU General Public License
@@ -29,6 +30,9 @@ Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 ============================================================================
 */
 
+/* Casting to unsigned when shifting by 24 bits here is necessary to prevent UB
+ * caused by shifting outside the range of int on platforms where int is 32 bits.
+ */
 
 float BuffBigFloat (const unsigned char *buffer)
 {
@@ -38,13 +42,13 @@ float BuffBigFloat (const unsigned char *buffer)
                unsigned int i;
        }
        u;
-       u.i = (buffer[0] << 24) | (buffer[1] << 16) | (buffer[2] << 8) | buffer[3];
+       u.i = ((unsigned)buffer[0] << 24) | (buffer[1] << 16) | (buffer[2] << 8) | buffer[3];
        return u.f;
 }
 
 int BuffBigLong (const unsigned char *buffer)
 {
-       return (buffer[0] << 24) | (buffer[1] << 16) | (buffer[2] << 8) | buffer[3];
+       return ((unsigned)buffer[0] << 24) | (buffer[1] << 16) | (buffer[2] << 8) | buffer[3];
 }
 
 short BuffBigShort (const unsigned char *buffer)
@@ -60,13 +64,13 @@ float BuffLittleFloat (const unsigned char *buffer)
                unsigned int i;
        }
        u;
-       u.i = (buffer[3] << 24) | (buffer[2] << 16) | (buffer[1] << 8) | buffer[0];
+       u.i = ((unsigned)buffer[3] << 24) | (buffer[2] << 16) | (buffer[1] << 8) | buffer[0];
        return u.f;
 }
 
 int BuffLittleLong (const unsigned char *buffer)
 {
-       return (buffer[3] << 24) | (buffer[2] << 16) | (buffer[1] << 8) | buffer[0];
+       return ((unsigned)buffer[3] << 24) | (buffer[2] << 16) | (buffer[1] << 8) | buffer[0];
 }
 
 short BuffLittleShort (const unsigned char *buffer)
@@ -286,7 +290,7 @@ int MSG_ReadLittleLong (sizebuf_t *sb)
                return -1;
        }
        sb->readcount += 4;
-       return sb->data[sb->readcount-4] | (sb->data[sb->readcount-3]<<8) | (sb->data[sb->readcount-2]<<16) | (sb->data[sb->readcount-1]<<24);
+       return sb->data[sb->readcount-4] | (sb->data[sb->readcount-3]<<8) | (sb->data[sb->readcount-2]<<16) | ((unsigned)sb->data[sb->readcount-1]<<24);
 }
 
 int MSG_ReadBigLong (sizebuf_t *sb)
@@ -297,7 +301,7 @@ int MSG_ReadBigLong (sizebuf_t *sb)
                return -1;
        }
        sb->readcount += 4;
-       return (sb->data[sb->readcount-4]<<24) + (sb->data[sb->readcount-3]<<16) + (sb->data[sb->readcount-2]<<8) + sb->data[sb->readcount-1];
+       return ((unsigned)sb->data[sb->readcount-4]<<24) + (sb->data[sb->readcount-3]<<16) + (sb->data[sb->readcount-2]<<8) + sb->data[sb->readcount-1];
 }
 
 float MSG_ReadLittleFloat (sizebuf_t *sb)
@@ -313,7 +317,7 @@ float MSG_ReadLittleFloat (sizebuf_t *sb)
                return -1;
        }
        sb->readcount += 4;
-       dat.l = sb->data[sb->readcount-4] | (sb->data[sb->readcount-3]<<8) | (sb->data[sb->readcount-2]<<16) | (sb->data[sb->readcount-1]<<24);
+       dat.l = sb->data[sb->readcount-4] | (sb->data[sb->readcount-3]<<8) | (sb->data[sb->readcount-2]<<16) | ((unsigned)sb->data[sb->readcount-1]<<24);
        return dat.f;
 }
 
@@ -330,7 +334,7 @@ float MSG_ReadBigFloat (sizebuf_t *sb)
                return -1;
        }
        sb->readcount += 4;
-       dat.l = (sb->data[sb->readcount-4]<<24) | (sb->data[sb->readcount-3]<<16) | (sb->data[sb->readcount-2]<<8) | sb->data[sb->readcount-1];
+       dat.l = ((unsigned)sb->data[sb->readcount-4]<<24) | (sb->data[sb->readcount-3]<<16) | (sb->data[sb->readcount-2]<<8) | sb->data[sb->readcount-1];
        return dat.f;
 }