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FS-8853 enable change of resolution of fast arc cos table 

It is possible now to apply lower resolution to mapping
of float-integer-float and decrease size of mapped file.
This commit is contained in:
Piotr Gregor 2016-03-11 19:27:21 +00:00
parent 566cc41908
commit da7be641ba
1 changed files with 172 additions and 27 deletions
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199
src/mod/applications/mod_avmd/fast_acosf.c
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@ -20,41 +20,71 @@
#ifdef FASTMATH
#define SIGN_MASK (0x80000000)
#define DATA_MASK (0x07FFFFF8)
#define SIGN_UNPACK_MASK (0x01000000)
#define DATA_UNPACK_MASK (0x00FFFFFF)
#define VARIA_DATA_MASK (0x87FFFFF8)
#define CONST_DATA_MASK (0x38000000)
#define ACOS_TABLE_LENGTH (1 << 25)
#define ACOS_TABLE_FILENAME "/tmp/acos_table.dat"
typedef union {
uint32_t i;
float f;
} float_conv_t;
#ifdef FAST_ACOSF_TESTING
static float strip_float(float f);
#endif
/*
* Manipulate these parameters to change
* mapping's resolution. The sine tone
* of 1600Hz is detected even with 20
* bits discarded in float integer representation
* with only slightly increased amount of false
* positives (keeping variance threshold on 0.0001).
* 12 bits seem to be good choice when there is
* a need to compute faster and/or decrease mapped file
* size on disk while keeping false positives low.
*/
#define ACOS_TABLE_CONST_EXPONENT (0x70)
#define ACOS_TABLE_CONST_EXPONENT_BITS (3)
#define ACOS_TABLE_DISCARDED_BITS (3)
/* rosolution:
3: 15 728 640 indices spreading range [0.0, 1.0], table size on disk 134 217 728 bytes (default)
4: 7 364 320 indices spreading range [0.0, 1.0], table size on disk 67 108 864 bytes
5: 3 932 160 indices spreading range [0.0, 1.0], table size on disk 33 554 432 bytes
12: 30 720 indices spreading range [0.0, 1.0], table size on disk 262 144 bytes
16: 1 920 indices spreading range [0.0, 1.0], table size on disk 16 384 bytes
20: 120 indices spreading range [0.0, 1.0], table size on disk 1 024 bytes
24: 7 indices spreading range [0.0, 1.0], table size on disk 64 bytes
26: 1 indices spreading range [0.0, 1.0], table size on disk 16 bytes
*/
#define ACOS_TABLE_FREE_EXPONENT_BITS (7 - ACOS_TABLE_CONST_EXPONENT_BITS)
#define ACOS_TABLE_DATA_BITS (31 - ACOS_TABLE_CONST_EXPONENT_BITS - ACOS_TABLE_DISCARDED_BITS)
#define ACOS_TABLE_LENGTH (1 << (31 - ACOS_TABLE_CONST_EXPONENT_BITS - ACOS_TABLE_DISCARDED_BITS))
#define VARIA_DATA_MASK (0x87FFFFFF & ~((1 << ACOS_TABLE_DISCARDED_BITS) - 1))
#define CONST_DATA_MASK (((1 << ACOS_TABLE_CONST_EXPONENT_BITS) - 1) \
<< (ACOS_TABLE_DATA_BITS - 1 + ACOS_TABLE_DISCARDED_BITS))
#define SIGN_UNPACK_MASK (1 << (ACOS_TABLE_DATA_BITS - 1))
#define DATA_UNPACK_MASK ((1 << (ACOS_TABLE_DATA_BITS - 1)) - 1)
#define SIGN_MASK (0x80000000)
#define DATA_MASK (DATA_UNPACK_MASK << ACOS_TABLE_DISCARDED_BITS)
#define ACOS_TABLE_FILENAME "/tmp/acos_table.dat"
static uint32_t index_from_float(float f);
static float float_from_index(uint32_t d);
static float *acos_table = NULL;
static int acos_fd = -1;
#ifdef FAST_ACOSF_TESTING
static float strip_float(float f)
{
float_conv_t d;
d.i = d.i & (VARIA_DATA_MASK | CONST_DATA_MASK);
#define INF(x) printf("[%s] [%u]\n", #x, x)
#define INFX(x) printf("[%s] [%08x]\n", #x, x)
static void
debug_print(void);
static void
dump_table_summary(void);
#endif /* FAST_ACOSF_TESTING */
return d.i;
}
#endif
extern void compute_table(void)
{
@ -114,23 +144,138 @@ extern float fast_acosf(float x)
return acos_table[index_from_float(x)];
}
static uint32_t index_from_float(float f)
{
float_conv_t d;
d.f = f;
return ((d.i & SIGN_MASK) >> 7) | ((d.i & DATA_MASK) >> 3);
return ((d.i & SIGN_MASK) >> (32 - ACOS_TABLE_DATA_BITS)) |
((d.i & DATA_MASK) >> ACOS_TABLE_DISCARDED_BITS);
}
static float float_from_index(uint32_t d)
{
float_conv_t f;
f.i = ((d & SIGN_UNPACK_MASK) << 7) | ((d & DATA_UNPACK_MASK) << 3) | CONST_DATA_MASK;
f.i = ((d & SIGN_UNPACK_MASK) << (32 - ACOS_TABLE_DATA_BITS)) |
((d & DATA_UNPACK_MASK) << ACOS_TABLE_DISCARDED_BITS) | CONST_DATA_MASK;
return f.f;
}
#ifdef FAST_ACOSF_TESTING
#define INF(x) printf("[%s] [%u]\n", #x, x)
#define INFX(x) printf("[%s] [%08x]\n", #x, x)
static void
debug_print(void)
{
INF(ACOS_TABLE_CONST_EXPONENT);
INF(ACOS_TABLE_CONST_EXPONENT_BITS);
INF(ACOS_TABLE_FREE_EXPONENT_BITS);
INF(ACOS_TABLE_DISCARDED_BITS);
INF(ACOS_TABLE_DATA_BITS);
INF(ACOS_TABLE_LENGTH);
INFX(VARIA_DATA_MASK);
INFX(CONST_DATA_MASK);
INFX(SIGN_UNPACK_MASK);
INFX(DATA_UNPACK_MASK);
INFX(SIGN_MASK);
INFX(DATA_MASK);
}
static void
dump_table_summary(void)
{
uint32_t i, i_0, i_1, di;
float f;
i = 1;
i_0 = index_from_float(0.0);
i_1 = index_from_float(1.0);
di = (i_1 - i_0)/100;
if (di == 0) di = 1;
for (; i < ACOS_TABLE_LENGTH; i += di )
{
f = float_from_index(i);
printf("-01i[%.10u] : ffi[%f] fa[%f] acos[%f]\n",
i, f, fast_acosf(f), acos(f));
}
i = 1;
for (; i < ACOS_TABLE_LENGTH; i = (i << 1))
{
f = fast_acosf(float_from_index(i));
printf("--i[%.10u] : fa[%f] ffi[%f]\n",
i, f, float_from_index(i));
}
f = 0.0;
printf("i [%d] from float [%f]\n", index_from_float(f), f);
f = 0.1;
printf("i [%d] from float [%f]\n", index_from_float(f), f);
f = 0.2;
printf("i [%d] from float [%f]\n", index_from_float(f), f);
f = 0.3;
printf("i [%d] from float [%f]\n", index_from_float(f), f);
f = 0.4;
printf("i [%d] from float [%f]\n", index_from_float(f), f);
f = 0.5;
printf("i [%d] from float [%f]\n", index_from_float(f), f);
f = 0.6;
printf("i [%d] from float [%f]\n", index_from_float(f), f);
f = 0.7;
printf("i [%d] from float [%f]\n", index_from_float(f), f);
f = 7.5;
printf("i [%d] from float [%f]\n", index_from_float(f), f);
f = 0.8;
printf("i [%d] from float [%f]\n", index_from_float(f), f);
f = 0.9;
printf("i [%d] from float [%f]\n", index_from_float(f), f);
f = 0.95;
printf("i [%d] from float [%f]\n", index_from_float(f), f);
f = 0.99;
printf("i [%d] from float [%f]\n", index_from_float(f), f);
f = 1.0;
printf("i [%d] from float [%f]\n", index_from_float(f), f);
f = 1.1;
printf("i [%d] from float [%f]\n", index_from_float(f), f);
f = 1.2;
printf("i [%d] from float [%f]\n", index_from_float(f), f);
f = 0.0;
printf("i [%d] from float [%f]\n", index_from_float(f), f);
f = -0.1;
printf("i [%d] from float [%f]\n", index_from_float(f), f);
f = -0.2;
printf("i [%d] from float [%f]\n", index_from_float(f), f);
f = -0.3;
printf("i [%d] from float [%f]\n", index_from_float(f), f);
f = -0.4;
printf("i [%d] from float [%f]\n", index_from_float(f), f);
f = -0.5;
printf("i [%d] from float [%f]\n", index_from_float(f), f);
f = -0.6;
printf("i [%d] from float [%f]\n", index_from_float(f), f);
f = -0.7;
printf("i [%d] from float [%f]\n", index_from_float(f), f);
f = -7.5;
printf("i [%d] from float [%f]\n", index_from_float(f), f);
f = -0.8;
printf("i [%d] from float [%f]\n", index_from_float(f), f);
f = -0.9;
printf("i [%d] from float [%f]\n", index_from_float(f), f);
f = -0.95;
printf("i [%d] from float [%f]\n", index_from_float(f), f);
f = -0.99;
printf("i [%d] from float [%f]\n", index_from_float(f), f);
f = -1.0;
printf("i [%d] from float [%f]\n", index_from_float(f), f);
f = -1.1;
printf("i [%d] from float [%f]\n", index_from_float(f), f);
f = -1.2;
printf("i [%d] from float [%f]\n", index_from_float(f), f);
}
#endif /* FAST_ACOSF_TESTING */
#endif