esp-who/components/lib/include/dl_lib_matrixq.h

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2018-10-18 15:52:33 +08:00
#ifndef DL_LIB_MATRIXQ_H
#define DL_LIB_MATRIXQ_H
#include <stdint.h>
#include "dl_lib_matrix.h"
typedef int16_t qtp_t;
//Quantized matrix. Uses fixed numbers and has the storage for the rows/columns inverted
//for easy use as a multiplicand without stressing out the flash cache too much.
typedef struct {
int w;
int h;
int stride; //Normally equals h, not w!
int flags;
int exponent; //The values in items should be multiplied by pow(2,exponent) to get the real values.
qtp_t *itemq;
} dl_matrix2dq_t;
#define DL_QTP_SHIFT 15
#define DL_QTP_RANGE ((1<<DL_QTP_SHIFT)-1)
#define DL_ITMQ(m, x, y) m->itemq[(y)+(x)*m->stride]
#define DL_QTP_EXP_NA 255 //non-applicable exponent because matrix is null
#define DL_SHIFT_AUTO 32
/**
* @info About quantized matrices and shift values
*
* Grab a coffee (or tea, or hot water) and sit down when you read this for the first
* time. Quantized matrices can speed up your operations, but come with some quirks, and
* it's good to understand how they work before using them.
*
* The data in the quantized matrix type is stored similarily to floating-point types:
* when storing a real value, the value is stored as a mantissa (base number) and an
* exponent. The 'real' value that can be re-derived from those two numbers is something
* similar to mantissa*2^exponent. Up to this point, there's not that much difference from
* the standard floating point implementations like e.g. IEEE-754.
*
* The difference with respect to quantized matrices is that for a quantized matrix, it is
* assumed all values stored have more-or-less the same order of magnitude. This allows the
* matrix to only store all the mantissas, while the exponents are shared; there is only one
* exponent for the entire matrix. This makes it quicker to handle matrix operations - the
* logic to fix the exponents only needs to happen once, while the rest can be done in simple
* integer arithmetic. It also nets us some memory savings - while normally a floating point
* number is 32-bit, storing only 16-bit mantissas as the matrix items almost halves the
* memory requirements.
*
* While most of the details of handling the intricacies of the quantized matrixes are done
* transparently by the code in dl_lib_matrixq.c, some implementation details leak out,
* specifically in places where addition/subtraction/division happens.
*
* The problem is that the routines do not know what the size of the resulting operation is. For
* instance, when adding two matrices of numbers, the resulting numbers *could* be large enough
* to overflow the mantissa of the result if the exponent is the same. However, if by default we
* assume the mantissas needs to be scaled back, we may lose precision.
*
* In order to counter this, all operations that have this issue have a ``shift`` argument. If
* the argument is zero, the routine will be conservative, that is, increase the exponent of
* the result to such an extent it's mathematically impossible a value in the result will exceed
* the maximum value that can be stored. However, when this argument is larger than zero, the
* algorithm will hold back on this scaling by the indicated amount of bits, preserving precision
* but increasing the chance of some of the calculated values not fitting in the mantissa anymore.
* If this happens, the value will be clipped to the largest (or, for negative values, smallest)
* value possible. (Neural networks usually are okay with this happening for a limited amount
* of matrix indices).
*
* For deciding on these shift values, it is recommended to start with a shift value of one, then
* use dl_matrixq_check_sanity on the result. If this indicates clipping, lower the shift value.
* If it indicates bits are under-used, increase it. Note that for adding and subtraction, only
* shift values of 0 or 1 make sense; these routines will error out if you try to do something
* else.
*
* For neural networks and other noise-tolerant applications, note that even when
* dl_matrixq_check_sanity does not indicate any problems, twiddling with the shift value may lead
* to slightly improved precision. Feel free to experiment.
**/
/**
* @brief Allocate a matrix
*
* @param w Width of the matrix
* @param h Height of the matrix
* @return The matrix, or NULL if out of memory
*/
dl_matrix2dq_t *dl_matrixq_alloc(int w, int h);
/**
* @brief Convert a floating-point matrix to a quantized matrix
*
* @param m Floating-point matrix to convert
* @param out Quantized matrix to re-use. If NULL, allocate a new one.
* @Return The quantized version of the floating-point matrix
*/
dl_matrix2dq_t *dl_matrixq_from_matrix2d(const dl_matrix2d_t *m, dl_matrix2dq_t *out);
/**
* TODO: DESCRIBE THIS FUNCTION
*/
dl_matrix2dq_t *dl_matrixq_from_matrix2d_by_qmf(const dl_matrix2d_t *m, dl_matrix2dq_t *out, int m_bit, int f_bit);
/**
* @brief Convert a quantized matrix to a floating-point one.
*
* @param m Floating-point matrix to convert
* @param out Quantized matrix to re-use. If NULL, allocate a new one.
* @Return The quantized version of the floating-point matrix
**/
dl_matrix2d_t *dl_matrix2d_from_matrixq(const dl_matrix2dq_t *m, dl_matrix2d_t *out);
/**
* @brief Free a quantized matrix
* Frees the matrix structure and (if it doesn't have the DL_MF_FOREIGNDATA flag set) the m->items space as well.
*
* @param m Matrix to free
*/
void dl_matrixq_free(dl_matrix2dq_t *m);
/**
* @brief Zero out the matrix
* Sets all entries in the matrix to 0.
*
* @param m Matrix to zero
*/
void dl_matrixq_zero(dl_matrix2dq_t *m);
/**
* @brief Do a dotproduct of two quantized matrices : res=a.b, Result is a fixed-point matrix.
*
* @param a First multiplicand
* @param b Second multiplicand
* @param res Dotproduct data. *Must* be a *different* matrix from a or b!
* @param shift Shift ratio
*/
void dl_matrixq_dot(const dl_matrix2dq_t *a, const dl_matrix2dq_t *b, dl_matrix2dq_t *res, int shift);
/**
* @brief Do a dotproduct of two quantized matrices: res=a.b, Result is a floating-point matrix.
*
* @param a First multiplicand
* @param b Second multiplicand
* @param res Dotproduct data. *Must* be a *different* matrix from a or b!
*/
void dl_matrixq_dot_matrix_out(const dl_matrix2dq_t *a, const dl_matrix2dq_t *b, dl_matrix2d_t *res);
/**
* @brief Do a dotproduct of two quantized matrices : res=a.b. This always uses the simple & stupid C algo for the dot product.
*
* Result is a fixed-point matrix.
*
* Use this only if you expect something is wrong with the accelerated routines that dl_matrixq_dot calls; this function can be
* much slower than dl_matrixq_dot .
*
* @param a First multiplicand
* @param b Second multiplicand
* @param res Dotproduct data. *Must* be a *different* matrix from a or b!
* @param shift Shift ratio
*/
void dl_matrixq_dot_c_impl(const dl_matrix2dq_t *a, const dl_matrix2dq_t *b, dl_matrix2dq_t *res, int shift);
/**
* @brief Do a dotproduct of two quantized matrices : res=a.b. This always uses the simple & stupid C algo for the dot product.
*
* Result is a floating-point matrix.
*
* Use this only if you expect something is wrong with the accelerated routines that dl_matrixq_dot_matrix_out calls; this function can be
* much slower than dl_matrixq_dot_matrix_out.
*
* @param a First multiplicand
* @param b Second multiplicand
* @param res Dotproduct data. *Must* be a *different* matrix from a or b!
*/
void dl_matrixq_dot_matrix_out_c_impl(const dl_matrix2dq_t *a, const dl_matrix2dq_t *b, dl_matrix2d_t *res);
/**
* @brief Do a dotproduct of a floating point and a quantized matrix. Result is a floating-point matrix.
*
* @param a First multiplicand; float matrix
* @param b Second multiplicand; quantized matrix
* @param res Dotproduct data; float matrix. *Must* be a *different* matrix from a or b!
*/
void dl_matrix_matrixq_dot(const dl_matrix2d_t *a, const dl_matrix2dq_t *b, dl_matrix2d_t *res);
/**
* @brief Print the contents of a quantized matrix to stdout. Used for debugging.
*
* @param a The matrix to print.
*/
void dl_printmatrixq(const dl_matrix2dq_t *a);
/**
* @brief Add a pair of quantizedmatrices item-by-item: res=a-b
*
* @param a First matrix
* @param b Second matrix
* @param res Added data. Can be equal to a or b to overwrite that.
* @param shift Shift value. Only 0 or 1 makes sense here. <ToDo: check>
*/
void dl_matrixq_add(const dl_matrix2dq_t *a, const dl_matrix2dq_t *b, dl_matrix2dq_t *res, int shift);
/**
* @brief Generate a new matrix using a range of items from an existing matrix.
* When using this, the data of the new matrix is not allocated/copied but it re-uses a pointer
* to the existing data. Changing the data in the resulting matrix, as a result, will also change
* the data in the existing matrix that has been sliced.
*
* @Warning In contrast to the floating point equivalent of this function, the fixed-point version
* of this has the issue that as soon as the output exponent of one of the slices changes, the data
* in the sliced matrix gets corrupted (because the exponent of that matrix is still the same.) If you
* use this function, either treat the slices as read-only, or assume the sliced matrix contains
* garbage after modifying the data in one of the slices.
*
* @param x X-offset of the origin of the returned matrix within the sliced matrix
* @param y Y-offset of the origin of the returned matrix within the sliced matrix
* @param w Width of the resulting matrix
* @param h Height of the resulting matrix
* @param in Old matrix (with foreign data) to re-use. Passing NULL will allocate a new matrix.
* @return The resulting slice matrix, or NULL if out of memory
*/
dl_matrix2dq_t *dl_matrixq_slice(const dl_matrix2dq_t *src, int x, int y, int w, int h, dl_matrix2dq_t *in);
/**
* @brief select a range of items from an existing matrix and flatten them into one dimension.
*
* @Warning The results are flattened in row-major order.
*
* @param x X-offset of the origin of the returned matrix within the sliced matrix
* @param y Y-offset of the origin of the returned matrix within the sliced matrix
* @param w Width of the resulting matrix
* @param h Height of the resulting matrix
* @param in Old matrix to re-use. Passing NULL will allocate a new matrix.
* @return The resulting flatten matrix, or NULL if out of memory
*/
dl_matrix2dq_t *dl_matrixq_flatten(const dl_matrix2dq_t *src, int x, int y, int w, int h, dl_matrix2dq_t *in);
/**
* @brief Subtract a quantized matrix from another, item-by-item: res=a-b
*
* @param a First matrix
* @param b Second matrix
* @param res Subtracted data. Can be equal to a or b to overwrite that.
* @param shift Shift value. Only 0 or 1 makes sense here. <ToDo: check>
*/
void dl_matrixq_sub(const dl_matrix2dq_t *a, const dl_matrix2dq_t *b, dl_matrix2dq_t *res, int shift);
/**
* @brief Multiply a pair of quantized matrices item-by-item: res=a*b
*
* @param a First multiplicand
* @param b Second multiplicand
* @param res Multiplicated data. Can be equal to a or b to overwrite that matrix.
*/
void dl_matrixq_mul(const dl_matrix2dq_t *a, const dl_matrix2dq_t *b, dl_matrix2dq_t *res);
/**
* @brief Divide a pair of quantized matrices item-by-item: res=a/b
*
* @param a First matrix
* @param b Second matrix
* @param res Divided data. Can be equal to a or b to overwrite that.
*/
void dl_matrixq_div(const dl_matrix2dq_t *a, const dl_matrix2dq_t *b, dl_matrix2dq_t *out, int shift);
/**
* @brief Check if two quantized matrices have the same shape, that is, the same amount of
* rows and columns
*
* @param a First of the two matrices to compare
* @param b Second of the two matrices to compare
* @return true if the two matrices are shaped the same, false otherwise.
*/
int dl_matrixq_same_shape(const dl_matrix2dq_t *a, const dl_matrix2dq_t *b);
/**
* @brief Concatenate the rows of two quantized matrices into a new matrix
*
* @param a First matrix
* @param b Second matrix
* @return A newly allocated quantized matrix with as values a|b
*/
dl_matrix2dq_t *dl_matrixq_concat(const dl_matrix2dq_t *a, const dl_matrix2dq_t *b);
/**
* @brief Add a constant to every item of the quantized matrix
*
* @param subj Matrix to add the constant to
* @param add The constant
*/
void dl_matrixq_add_const(dl_matrix2dq_t *subj, const fptp_t add, int shift);
/**
* @brief Check the sanity of a quantized matrix
*
* Due to the nature of quantized matrices, depending on the calculations a quantized
* matrix is the result of and the shift values chosen in those calculations, a quantized
* matrix may have an exponent and mantissas that lead to a loss of precision, either because
* most significant mantissa bits are unused, or because a fair amount of mantissas are
* clipped. This function checks if this is the case and will report a message to stdout
* if significant loss of precision is detected.
*
* @param m The quantized matrix to check
* @param name A string to be displayed in the message if the sanity check fails
* @return True if matrix is sane, false otherwise
**/
int dl_matrixq_check_sanity(dl_matrix2dq_t *m, const char *name);
/**
* @brief re-adjust the exponent of the matrix to fit the mantissa better
*
* This function will shift up all the data in the mantissas so there are no
* most-significant bits that are unused in all mantissas. It will also adjust
* the exponent to keep the actua values in the matrix the same.
*
* Some operations done on a matrix, especially operations that re-use the
* result of earlier operations done in the same way, can lead to the loss of
* data because the exponent of the quantized matrix is never re-adjusted. You
* can do that implicitely by calling this function.
*
* @param m The matrix to re-adjust
**/
void dl_matrixq_readjust_exp(dl_matrix2dq_t *m);
/**
* @brief Get the floating-point value of a specific item from the quantized matrix
*
* @param m Matrix to access
* @param x Column address
* @param y Row address
* @return Value in that position
*/
fptp_t dl_matrixq_get(const dl_matrix2dq_t *m, const int x, const int y);
/**
* @brief Set a specific item in the quantized matrix to the given
* floating-point value
*
* @warning If the given value is more than the exponent in the quantized matrix
* allows for, all mantissas in the matrix will be shifted down to make the value
* 'fit'. If, however, the exponent is such that the value would result in a
* quantized mantissa of 0, nothing is done.
*
* @param m Matrix to access
* @param x Column address
* @param y Row address
* @param val Value to write to that position
*/
void dl_matrixq_set(dl_matrix2dq_t *m, const int x, const int y, fptp_t val);
#endif