NN: apply q7 fix from upstream.

This commit is contained in:
iabdalkader 2018-05-29 04:41:26 +02:00
parent fd5cc31f49
commit 83dd9bafd4

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@ -21,7 +21,7 @@
* Title: arm_softmax_q7.c * Title: arm_softmax_q7.c
* Description: Q7 softmax function * Description: Q7 softmax function
* *
* $Date: 17. January 2018 * $Date: 20. February 2018
* $Revision: V.1.0.0 * $Revision: V.1.0.0
* *
* Target Processor: Cortex-M cores * Target Processor: Cortex-M cores
@ -64,43 +64,56 @@ void arm_softmax_q7(const q7_t * vec_in, const uint16_t dim_vec, q7_t * p_out)
{ {
q31_t sum; q31_t sum;
int16_t i; int16_t i;
q15_t min, max; uint8_t shift;
max = -257; q15_t base;
min = 257; base = -257;
/* We first search for the maximum */
for (i = 0; i < dim_vec; i++) for (i = 0; i < dim_vec; i++)
{ {
if (vec_in[i] > max) if (vec_in[i] > base)
{ {
max = vec_in[i]; base = vec_in[i];
}
if (vec_in[i] < min)
{
min = vec_in[i];
} }
} }
/* we ignore really small values /*
* anyway, they will be 0 after shrinking * So the base is set to max-8, meaning
* to q7_t * that we ignore really small values.
* anyway, they will be 0 after shrinking to q7_t.
*/ */
if (max - min > 8) base = base - 8;
{
min = max - 8;
}
sum = 0; sum = 0;
for (i = 0; i < dim_vec; i++) for (i = 0; i < dim_vec; i++)
{ {
sum += 0x1 << (vec_in[i] - min); if (vec_in[i] > base)
{
shift = (uint8_t)__USAT(vec_in[i] - base, 5);
sum += 0x1 << shift;
}
} }
/* This is effectively (0x1 << 20) / sum */
int output_base = 0x100000 / sum;
/*
* Final confidence will be output_base >> ( 13 - (vec_in[i] - base) )
* so 128 (0x1<<7) -> 100% confidence when sum = 0x1 << 8, output_base = 0x1 << 12
* and vec_in[i]-base = 8
*/
for (i = 0; i < dim_vec; i++) for (i = 0; i < dim_vec; i++)
{ {
/* we leave 7-bit dynamic range, so that 128 -> 100% confidence */ if (vec_in[i] > base)
p_out[i] = (q7_t) __SSAT(((0x1 << (vec_in[i] - min + 20)) / sum) >> 13, 8); {
/* Here minimum value of 13+base-vec_in[i] will be 5 */
shift = (uint8_t)__USAT(13+base-vec_in[i], 5);
p_out[i] = (q7_t) __SSAT((output_base >> shift), 8);
} else {
p_out[i] = 0;
}
} }
} }
/** /**