Added MMX code and detection of MMX capable CPU

diff --git a/src/pcm/pcm_dmix.c b/src/pcm/pcm_dmix.c
index de68f7c0cdd4a47dc3c362336aedbbe0eb879f04..cc22a3c12efe419c92e53a42dc137f5b57758b8f 100644 (file)
--- a/src/pcm/pcm_dmix.c
+++ b/src/pcm/pcm_dmix.c
@@ -67,6 +67,11 @@ const char *_snd_module_pcm_dmix = "";
  
 int snd_timer_async(snd_timer_t *timer, int sig, pid_t pid);
 
+typedef void (mix_areas1_t)(unsigned int size,
+                       volatile signed short *dst, signed short *src,
+                       volatile signed int *sum, unsigned int dst_step,
+                       unsigned int src_step, unsigned int sum_step);
+
 /*
  *
  */
@@ -121,6 +126,7 @@ typedef struct {
        pid_t server_pid;
        snd_timer_t *timer; /* timer used as poll_fd */
        int interleaved; /* we have interleaved buffer */
+       mix_areas1_t *mix_areas1;
 } snd_pcm_dmix_t;
 
 /*
@@ -562,7 +568,12 @@ static int check_interleave(snd_pcm_dmix_t *dmix)
  */
 
 #ifdef __i386__
+
 #define ADD_AND_SATURATE
+
+/*
+ *  for plain i386
+ */
 static void mix_areas1(unsigned int size,
                       volatile signed short *dst, signed short *src,
                       volatile signed int *sum, unsigned int dst_step,
@@ -677,6 +688,117 @@ static void mix_areas1(unsigned int size,
                : "esi", "edi", "edx", "ecx", "ebx", "eax"
        );
 }
+
+/*
+ *  MMX optimized
+ */
+static void mix_areas1_mmx(unsigned int size,
+                          volatile signed short *dst, signed short *src,
+                          volatile signed int *sum, unsigned int dst_step,
+                          unsigned int src_step, unsigned int sum_step)
+{
+       /*
+        *  ESI - src
+        *  EDI - dst
+        *  EBX - sum
+        *  ECX - old sample
+        *  EAX - sample / temporary
+        *  EDX - size
+        */
+       __asm__ __volatile__ (
+               "\n"
+
+               /*
+                *  initialization, load EDX, ESI, EDI, EBX registers
+                */
+               "\tmovl %0, %%edx\n"
+               "\tmovl %1, %%edi\n"
+               "\tmovl %2, %%esi\n"
+               "\tmovl %3, %%ebx\n"
+
+               /*
+                * while (size-- > 0) {
+                */
+               "\tcmp $0, %%edx\n"
+               "jz 6f\n"
+
+               "1:"
+
+               /*
+                *   sample = *src;
+                *   if (cmpxchg(*dst, 0, 1) == 0)
+                *     sample -= *sum;
+                *   xadd(*sum, sample);
+                */
+               "\tmovw $0, %%ax\n"
+               "\tmovw $1, %%cx\n"
+               "\tlock; cmpxchgw %%cx, (%%edi)\n"
+               "\tmovswl (%%esi), %%ecx\n"
+               "\tjnz 2f\n"
+               "\tsubl (%%ebx), %%ecx\n"
+               "2:"
+               "\tlock; addl %%ecx, (%%ebx)\n"
+
+               /*
+                *   do {
+                *     sample = old_sample = *sum;
+                *     saturate(v);
+                *     *dst = sample;
+                *   } while (v != *sum);
+                */
+
+               "3:"
+               "\tmovl (%%ebx), %%ecx\n"
+               "\tmovd %%ecx, %%mm0\n"
+               "\tpackssdw %%mm1, %%mm0\n"
+               "\tmovd %%mm0, %%eax\n"
+               "\tmovw %%ax, (%%edi)\n"
+               "\tcmpl %%ecx, (%%ebx)\n"
+               "\tjnz 3b\n"
+
+               /*
+                * while (size-- > 0)
+                */
+               "\tadd %4, %%edi\n"
+               "\tadd %5, %%esi\n"
+               "\tadd %6, %%ebx\n"
+               "\tdecl %%edx\n"
+               "\tjnz 1b\n"
+               "\tjmp 6f\n"
+
+               "6:"
+               
+               "\temms\n"
+
+               : /* no output regs */
+               : "m" (size), "m" (dst), "m" (src), "m" (sum), "m" (dst_step), "m" (src_step), "m" (sum_step)
+               : "esi", "edi", "edx", "ecx", "ebx", "eax"
+       );
+}
+ 
+static void mix_select_callbacks(snd_pcm_dmix_t *dmix)
+{
+       FILE *in;
+       char line[255];
+       
+       /* safe settings for all i386 CPUs */
+       dmix->mix_areas1 = mix_areas1;
+       /* try to determine, if we have a MMX capable CPU */
+       in = fopen("/proc/cpuinfo", "r");
+       if (in == NULL)
+               return;
+       while (!feof(in)) {
+               fgets(line, sizeof(line), in);
+               if (!strncmp(line, "flags", 5)) {
+                       fclose(in);
+                       if (strstr(line, " mmx")) {
+                               // printf("Selecting MMX mix_areas1\n");
+                               dmix->mix_areas1 = mix_areas1_mmx;
+                       }
+                       return;
+               }
+       }
+}
 #endif
 
 #ifndef ADD_AND_SATURATE
@@ -708,6 +830,11 @@ static void mix_areas1(unsigned int size,
                ((char *)sum) += sum_step;              
        }
 }
+
+static void mix_select_callbacks(snd_pcm_dmix_t *dmix)
+{
+       dmix->mix_areas1 = mix_areas1;
+}
 #endif
 
 static void mix_areas(snd_pcm_dmix_t *dmix,
@@ -729,13 +856,13 @@ static void mix_areas(snd_pcm_dmix_t *dmix,
                 * process the all areas in one loop
                 * it optimizes the memory accesses for this case
                 */
-               mix_areas1(size * channels,
-                          ((signed short *)dst_areas[0].addr) + (dst_ofs * channels),
-                          ((signed short *)src_areas[0].addr) + (src_ofs * channels),
-                          dmix->sum_buffer + (dst_ofs * channels),
-                          sizeof(signed short),
-                          sizeof(signed short),
-                          sizeof(signed int));
+               dmix->mix_areas1(size * channels,
+                                ((signed short *)dst_areas[0].addr) + (dst_ofs * channels),
+                                ((signed short *)src_areas[0].addr) + (src_ofs * channels),
+                                dmix->sum_buffer + (dst_ofs * channels),
+                                sizeof(signed short),
+                                sizeof(signed short),
+                                sizeof(signed int));
                return;
        }
        for (chn = 0; chn < channels; chn++) {
@@ -744,7 +871,7 @@ static void mix_areas(snd_pcm_dmix_t *dmix,
                src = (signed short *)(((char *)src_areas[chn].addr + src_areas[chn].first / 8) + (src_ofs * src_step));
                dst = (signed short *)(((char *)dst_areas[chn].addr + dst_areas[chn].first / 8) + (dst_ofs * dst_step));
                sum = dmix->sum_buffer + channels * dst_ofs + chn;
-               mix_areas1(size, dst, src, sum, dst_step, src_step, channels * sizeof(signed int));
+               dmix->mix_areas1(size, dst, src, sum, dst_step, src_step, channels * sizeof(signed int));
        }
 }
 
@@ -1608,6 +1735,7 @@ int snd_pcm_dmix_open(snd_pcm_t **pcmp, const char *name,
        }
 
        check_interleave(dmix);
+       mix_select_callbacks(dmix);
                
        pcm->poll_fd = dmix->poll_fd;
        pcm->poll_events = POLLIN;      /* it's different than other plugins */