alsa-lib/src/pcm/pcm_dmix_x86_64.c

/*
 * optimized mixing code for x86-64
 */

#define MIX_AREAS1 mix_areas1
#define MIX_AREAS2 mix_areas2
#define MIX_AREAS3 mix_areas3
#define LOCK_PREFIX ""
#include "pcm_dmix_x86_64.h"
#undef MIX_AREAS1
#undef MIX_AREAS2
#undef MIX_AREAS3
#undef LOCK_PREFIX

#define MIX_AREAS1 mix_areas1_smp
#define MIX_AREAS2 mix_areas2_smp
#define MIX_AREAS3 mix_areas3_smp
#define LOCK_PREFIX "lock ; "
#include "pcm_dmix_x86_64.h"
#undef MIX_AREAS1
#undef MIX_AREAS2
#undef MIX_AREAS3
#undef LOCK_PREFIX
 
#define x86_64_dmix_supported_format \
	((1ULL << SND_PCM_FORMAT_S16_LE) |\
	 (1ULL << SND_PCM_FORMAT_S32_LE) |\
	 (1ULL << SND_PCM_FORMAT_S24_3LE))

#define dmix_supported_format \
	(x86_64_dmix_supported_format | generic_dmix_supported_format)

static void mix_select_callbacks(snd_pcm_direct_t *dmix)
{
	static int smp = 0;
	
	if (!((1ULL<< dmix->shmptr->s.format) & x86_64_dmix_supported_format)) {
		generic_mix_select_callbacks(dmix);
		return;
	}

	if (!smp) {
		FILE *in;
		char line[255];

		/* try to determine, if we have SMP */
		in = fopen("/proc/cpuinfo", "r");
		if (in) {
			while (!feof(in)) {
				fgets(line, sizeof(line), in);
				if (!strncmp(line, "processor", 9))
					smp++;
			}
			fclose(in);
		}
	}
	// printf("SMP: %i\n", smp);
	dmix->u.dmix.mix_areas1 = smp > 1 ? mix_areas1_smp : mix_areas1;
	dmix->u.dmix.mix_areas2 = smp > 1 ? mix_areas2_smp : mix_areas2;
	dmix->u.dmix.mix_areas3 = smp > 1 ? mix_areas3_smp : mix_areas3;
}