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Archive for October, 2007

FreeBSD 7 ip checksum patch

October 25th, 2007
No comments

Here is the patch that unbreaks checksums using compiler options like -march=pentium-mmx

--- src/sys/i386/i386/in_cksum.c        2005/03/02 21:33:25     1.28
+++ src/sys/i386/i386/in_cksum.c        2007/10/20 22:18:42     1.29
@@ -260,17 +260,6 @@ u_int in_cksum_hdr(const struct ip *ip)
  * reorder operations, this will generally take place in parallel with
  * other calculations.
  */
-#define ADD(n) __asm __volatile \
-               ("addl %1, %0" : "+r" (sum) : \
-               "g" (((const u_int32_t *)w)[n / 4]))
-#define ADDC(n)        __asm __volatile \
-               ("adcl %1, %0" : "+r" (sum) : \
-               "g" (((const u_int32_t *)w)[n / 4]))
-#define LOAD(n)        __asm __volatile \
-               ("" : : "r" (((const u_int32_t *)w)[n / 4]))
-#define MOP    __asm __volatile \
-               ("adcl         $0, %0" : "+r" (sum))
-
 u_short
 in_cksum_skip(m, len, skip)
        struct mbuf *m;
@@ -341,15 +330,24 @@ skip_start:
                 * Advance to a 486 cache line boundary.
                 */
                if (4 & (int) w && mlen >= 4) {
-                       ADD(0);
-                       MOP;
+                       __asm __volatile (
+                               "addl %1, %0\n"
+                               "adcl $0, %0"
+                               : "+r" (sum)
+                               : "g" (((const u_int32_t *)w)[0])
+                       );
                        w += 2;
                        mlen -= 4;
                }
                if (8 & (int) w && mlen >= 8) {
-                       ADD(0);
-                       ADDC(4);
-                       MOP;
+                       __asm __volatile (
+                               "addl %1, %0\n"
+                               "adcl %2, %0\n"
+                               "adcl $0, %0"
+                               : "+r" (sum)
+                               : "g" (((const u_int32_t *)w)[0]),
+                                 "g" (((const u_int32_t *)w)[1])
+                       );
                        w += 4;
                        mlen -= 8;
                }
@@ -379,45 +377,81 @@ skip_start:
                         * is initially 33 (not 32) to guaranteed that
                         * the LOAD(32) is within bounds.
                         */
-                       ADD(16);
-                       ADDC(0);
-                       ADDC(4);
-                       ADDC(8);
-                       ADDC(12);
-                       LOAD(32);
-                       ADDC(20);
-                       ADDC(24);
-                       ADDC(28);
-                       MOP;
+                       __asm __volatile (
+                               "addl %1, %0\n"
+                               "adcl %2, %0\n"
+                               "adcl %3, %0\n"
+                               "adcl %4, %0\n"
+                               "adcl %5, %0\n"
+                               "mov  %6, %%eax\n"
+                               "adcl %7, %0\n"
+                               "adcl %8, %0\n"
+                               "adcl %9, %0\n"
+                               "adcl $0, %0"
+                               : "+r" (sum)
+                               : "g" (((const u_int32_t *)w)[4]),
+                                 "g" (((const u_int32_t *)w)[0]),
+                                 "g" (((const u_int32_t *)w)[1]),
+                                 "g" (((const u_int32_t *)w)[2]),
+                                 "g" (((const u_int32_t *)w)[3]),
+                                 "g" (((const u_int32_t *)w)[8]),
+                                 "g" (((const u_int32_t *)w)[5]),
+                                 "g" (((const u_int32_t *)w)[6]),
+                                 "g" (((const u_int32_t *)w)[7])
+                               : "eax"
+                       );
                        w += 16;
                }
                mlen += 32 + 1;
                if (mlen >= 32) {
-                       ADD(16);
-                       ADDC(0);
-                       ADDC(4);
-                       ADDC(8);
-                       ADDC(12);
-                       ADDC(20);
-                       ADDC(24);
-                       ADDC(28);
-                       MOP;
+                       __asm __volatile (
+                               "addl %1, %0\n"
+                               "adcl %2, %0\n"
+                               "adcl %3, %0\n"
+                               "adcl %4, %0\n"
+                               "adcl %5, %0\n"
+                               "adcl %6, %0\n"
+                               "adcl %7, %0\n"
+                               "adcl %8, %0\n"
+                               "adcl $0, %0"
+                               : "+r" (sum)
+                               : "g" (((const u_int32_t *)w)[4]),
+                                 "g" (((const u_int32_t *)w)[0]),
+                                 "g" (((const u_int32_t *)w)[1]),
+                                 "g" (((const u_int32_t *)w)[2]),
+                                 "g" (((const u_int32_t *)w)[3]),
+                                 "g" (((const u_int32_t *)w)[5]),
+                                 "g" (((const u_int32_t *)w)[6]),
+                                 "g" (((const u_int32_t *)w)[7])
+                       );
                        w += 16;
                        mlen -= 32;
                }
                if (mlen >= 16) {
-                       ADD(0);
-                       ADDC(4);
-                       ADDC(8);
-                       ADDC(12);
-                       MOP;
+                       __asm __volatile (
+                               "addl %1, %0\n"
+                               "adcl %2, %0\n"
+                               "adcl %3, %0\n"
+                               "adcl %4, %0\n"
+                               "adcl $0, %0"
+                               : "+r" (sum)
+                               : "g" (((const u_int32_t *)w)[0]),
+                                 "g" (((const u_int32_t *)w)[1]),
+                                 "g" (((const u_int32_t *)w)[2]),
+                                 "g" (((const u_int32_t *)w)[3])
+                       );
                        w += 8;
                        mlen -= 16;
                }
                if (mlen >= 8) {
-                       ADD(0);
-                       ADDC(4);
-                       MOP;
+                       __asm __volatile (
+                               "addl %1, %0\n"
+                               "adcl %2, %0\n"
+                               "adcl $0, %0"
+                               : "+r" (sum)
+                               : "g" (((const u_int32_t *)w)[0]),
+                                 "g" (((const u_int32_t *)w)[1])
+                       );
                        w += 4;
                        mlen -= 8;
                }
 
 
--- src/sys/i386/include/in_cksum.h     2005/03/02 21:33:26     1.17
+++ src/sys/i386/include/in_cksum.h     2007/10/20 22:18:42     1.18
@@ -92,9 +92,12 @@ static __inline u_short
 in_addword(u_short sum, u_short b)
 {
        /* __volatile is necessary because the condition codes are used. */
-       __asm __volatile ("addw %1, %0" : "+r" (sum) : "r" (b));
-       __asm __volatile ("adcw $0, %0" : "+r" (sum));
-
+       __asm __volatile (
+               "addw %1, %0\n"
+               "adcw $0, %0"
+               : "+r" (sum)
+               : "r" (b)
+       );
        return (sum);
 }
 
@@ -102,10 +105,14 @@ static __inline u_short
 in_pseudo(u_int sum, u_int b, u_int c)
 {
        /* __volatile is necessary because the condition codes are used. */
-       __asm __volatile ("addl %1, %0" : "+r" (sum) : "g" (b));
-       __asm __volatile ("adcl %1, %0" : "+r" (sum) : "g" (c));
-       __asm __volatile ("adcl $0, %0" : "+r" (sum));
-
+       __asm __volatile (
+               "addl %1, %0\n"
+               "adcl %2, %0\n"
+               "adcl $0, %0"
+               : "+r" (sum)
+               : "g" (b),
+                 "g" (c)
+       );
        sum = (sum & 0xffff) + (sum >> 16);
        if (sum > 0xffff)
                sum -= 0xffff;

Code

Trixbox PBX + VMware = Choppy Audio

October 1st, 2007
No comments

I’ve discovered running trixbox with vmware can result in choppy system audio from the automated prompts, and pre-recordings on menus.

Here is how you fix it. You will need VMware workstation or Player, look for config.ini and add these:

host.cpukHz = "2000000"
host.noTSC = "TRUE"
ptsc.noTSC = "TRUE"

You will need to replace cpukHZ with your actual CPU speed. This disables using TSC from inside vmware and uses the PIT (power management timer) to do timekeeping, which will result in smoother playback of audio. The long term solution is wait until Windows 2008 Server comes out, and VMWare should hopefully support HPET.

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