src/multiarray/nditer_impl.h File Reference

#include "Python.h"
#include "structmember.h"
#include <numpy/ndarrayobject.h>
#include <numpy/npy_3kcompat.h>
#include "convert_datatype.h"
#include "lowlevel_strided_loops.h"

Go to the source code of this file.

Data Structures
struct	NpyIter_InternalOnly
struct	NpyIter_BD
struct	NpyIter_AD
Defines
#define	PY_SSIZE_T_CLEAN
#define	NPY_NO_DEPRECATED_API
#define	_MULTIARRAYMODULE
#define	NPY_IT_CONSTRUCTION_TIMING   0
#define	NPY_IT_TIME_POINT(var)
#define	NPY_IT_DBG_TRACING   0
#define	NPY_IT_DBG_PRINT(s)
#define	NPY_IT_DBG_PRINT1(s, p1)
#define	NPY_IT_DBG_PRINT2(s, p1, p2)
#define	NPY_IT_DBG_PRINT3(s, p1, p2, p3)
#define	NPY_INTP_ALIGNED(size)   ((size + 0x7)&(-0x8))
#define	NPY_ITFLAG_IDENTPERM   0x0001
#define	NPY_ITFLAG_NEGPERM   0x0002
#define	NPY_ITFLAG_HASINDEX   0x0004
#define	NPY_ITFLAG_HASMULTIINDEX   0x0008
#define	NPY_ITFLAG_FORCEDORDER   0x0010
#define	NPY_ITFLAG_EXLOOP   0x0020
#define	NPY_ITFLAG_RANGE   0x0040
#define	NPY_ITFLAG_BUFFER   0x0080
#define	NPY_ITFLAG_GROWINNER   0x0100
#define	NPY_ITFLAG_ONEITERATION   0x0200
#define	NPY_ITFLAG_DELAYBUF   0x0400
#define	NPY_ITFLAG_NEEDSAPI   0x0800
#define	NPY_ITFLAG_REDUCE   0x1000
#define	NPY_ITFLAG_REUSE_REDUCE_LOOPS   0x2000
#define	NPY_OP_ITFLAG_WRITE   0x01
#define	NPY_OP_ITFLAG_READ   0x02
#define	NPY_OP_ITFLAG_CAST   0x04
#define	NPY_OP_ITFLAG_BUFNEVER   0x08
#define	NPY_OP_ITFLAG_ALIGNED   0x10
#define	NPY_OP_ITFLAG_REDUCE   0x20
#define	NPY_OP_ITFLAG_VIRTUAL   0x40
#define	NPY_OP_ITFLAG_WRITEMASKED   0x80
#define	NIT_PERM_SIZEOF(itflags, ndim, nop)   NPY_INTP_ALIGNED(NPY_MAXDIMS)
#define	NIT_DTYPES_SIZEOF(itflags, ndim, nop)   ((NPY_SIZEOF_INTP)*(nop))
#define	NIT_RESETDATAPTR_SIZEOF(itflags, ndim, nop)   ((NPY_SIZEOF_INTP)*(nop+1))
#define	NIT_BASEOFFSETS_SIZEOF(itflags, ndim, nop)   ((NPY_SIZEOF_INTP)*(nop+1))
#define	NIT_OPERANDS_SIZEOF(itflags, ndim, nop)   ((NPY_SIZEOF_INTP)*(nop))
#define	NIT_OPITFLAGS_SIZEOF(itflags, ndim, nop)   (NPY_INTP_ALIGNED(nop))
#define	NIT_BUFFERDATA_SIZEOF(itflags, ndim, nop)   ((itflags&NPY_ITFLAG_BUFFER) ? ((NPY_SIZEOF_INTP)*(6 + 9*nop)) : 0)
#define	NIT_PERM_OFFSET()   (0)
#define	NIT_DTYPES_OFFSET(itflags, ndim, nop)
#define	NIT_RESETDATAPTR_OFFSET(itflags, ndim, nop)
#define	NIT_BASEOFFSETS_OFFSET(itflags, ndim, nop)
#define	NIT_OPERANDS_OFFSET(itflags, ndim, nop)
#define	NIT_OPITFLAGS_OFFSET(itflags, ndim, nop)
#define	NIT_BUFFERDATA_OFFSET(itflags, ndim, nop)
#define	NIT_AXISDATA_OFFSET(itflags, ndim, nop)
#define	NIT_ITFLAGS(iter)   ((iter)->itflags)
#define	NIT_NDIM(iter)   ((iter)->ndim)
#define	NIT_NOP(iter)   ((iter)->nop)
#define	NIT_MASKOP(iter)   ((iter)->maskop)
#define	NIT_ITERSIZE(iter)   (iter->itersize)
#define	NIT_ITERSTART(iter)   (iter->iterstart)
#define	NIT_ITEREND(iter)   (iter->iterend)
#define	NIT_ITERINDEX(iter)   (iter->iterindex)
#define	NIT_PERM(iter)
#define	NIT_DTYPES(iter)
#define	NIT_RESETDATAPTR(iter)
#define	NIT_BASEOFFSETS(iter)
#define	NIT_OPERANDS(iter)
#define	NIT_OPITFLAGS(iter)
#define	NIT_BUFFERDATA(iter)
#define	NIT_AXISDATA(iter)
#define	NBF_BUFFERSIZE(bufferdata)   ((bufferdata)->buffersize)
#define	NBF_SIZE(bufferdata)   ((bufferdata)->size)
#define	NBF_BUFITEREND(bufferdata)   ((bufferdata)->bufiterend)
#define	NBF_REDUCE_POS(bufferdata)   ((bufferdata)->reduce_pos)
#define	NBF_REDUCE_OUTERSIZE(bufferdata)   ((bufferdata)->reduce_outersize)
#define	NBF_REDUCE_OUTERDIM(bufferdata)   ((bufferdata)->reduce_outerdim)
#define	NBF_STRIDES(bufferdata)
#define	NBF_PTRS(bufferdata)
#define	NBF_REDUCE_OUTERSTRIDES(bufferdata)
#define	NBF_REDUCE_OUTERPTRS(bufferdata)
#define	NBF_READTRANSFERFN(bufferdata)
#define	NBF_READTRANSFERDATA(bufferdata)
#define	NBF_WRITETRANSFERFN(bufferdata)
#define	NBF_WRITETRANSFERDATA(bufferdata)
#define	NBF_BUFFERS(bufferdata)
#define	NAD_SHAPE(axisdata)   ((axisdata)->shape)
#define	NAD_INDEX(axisdata)   ((axisdata)->index)
#define	NAD_STRIDES(axisdata)
#define	NAD_PTRS(axisdata)
#define	NAD_NSTRIDES()   ((nop) + ((itflags&NPY_ITFLAG_HASINDEX) ? 1 : 0))
#define	NIT_AXISDATA_SIZEOF(itflags, ndim, nop)
#define	NIT_INDEX_AXISDATA(axisdata, index)
#define	NIT_ADVANCE_AXISDATA(axisdata, count)   axisdata = NIT_INDEX_AXISDATA(axisdata, count)
#define	NIT_SIZEOF_ITERATOR(itflags, ndim, nop)
Typedefs
typedef struct NpyIter_AD	NpyIter_AxisData
typedef struct NpyIter_BD	NpyIter_BufferData
Functions
NPY_NO_EXPORT void	npyiter_coalesce_axes (NpyIter *iter)
NPY_NO_EXPORT int	npyiter_allocate_buffers (NpyIter *iter, char **errmsg)
NPY_NO_EXPORT void	npyiter_goto_iterindex (NpyIter *iter, npy_intp iterindex)
NPY_NO_EXPORT void	npyiter_copy_from_buffers (NpyIter *iter)
NPY_NO_EXPORT void	npyiter_copy_to_buffers (NpyIter *iter, char **prev_dataptrs)

---

Define Documentation

#define _MULTIARRAYMODULE

#define NAD_INDEX

(

axisdata

)

((axisdata)->index)

Referenced by npyiter_coalesce_axes(), and npyiter_iternext_sizeone().

#define NAD_NSTRIDES

(

)

((nop) + ((itflags&NPY_ITFLAG_HASINDEX) ? 1 : 0))

#define NAD_PTRS

(

axisdata

)

Value:

((char **) \
        &(axisdata)->ad_flexdata + 1*(nop+1))

#define NAD_SHAPE

(

axisdata

)

((axisdata)->shape)

Referenced by npyiter_coalesce_axes(), npyiter_find_best_axis_ordering(), npyiter_flip_negative_strides(), NpyIter_GetIndexPtr(), and NpyIter_RequiresBuffering().

#define NAD_STRIDES

(

axisdata

)

Value:

( \
        &(axisdata)->ad_flexdata + 0)

Referenced by npyiter_coalesce_axes().

#define NBF_BUFFERS

(

bufferdata

)

Value:

((char **) \
        (&(bufferdata)->bd_flexdata + 8*(nop)))

Referenced by NpyIter_Copy().

#define NBF_BUFFERSIZE

(

bufferdata

)

((bufferdata)->buffersize)

#define NBF_BUFITEREND

(

bufferdata

)

((bufferdata)->bufiterend)

Referenced by NpyIter_EnableExternalLoop(), and NpyIter_GotoIndex().

#define NBF_PTRS

(

bufferdata

)

Value:

((char **) \
        (&(bufferdata)->bd_flexdata + 1*(nop)))

Referenced by NpyIter_GetBufferSize(), and NpyIter_GotoIndex().

#define NBF_READTRANSFERDATA

(

bufferdata

)

Value:

((NpyAuxData **) \
        (&(bufferdata)->bd_flexdata + 5*(nop)))

Referenced by NpyIter_Copy().

#define NBF_READTRANSFERFN

(

bufferdata

)

Value:

((PyArray_StridedTransferFn **) \
        (&(bufferdata)->bd_flexdata + 4*(nop)))

#define NBF_REDUCE_OUTERDIM

(

bufferdata

)

((bufferdata)->reduce_outerdim)

#define NBF_REDUCE_OUTERPTRS

(

bufferdata

)

Value:

((char **) \
        (&(bufferdata)->bd_flexdata + 3*(nop)))

#define NBF_REDUCE_OUTERSIZE

(

bufferdata

)

((bufferdata)->reduce_outersize)

Referenced by npyiter_coalesce_axes().

#define NBF_REDUCE_OUTERSTRIDES

(

bufferdata

)

Value:

( \
        (&(bufferdata)->bd_flexdata + 2*(nop)))

#define NBF_REDUCE_POS

(

bufferdata

)

((bufferdata)->reduce_pos)

#define NBF_SIZE

(

bufferdata

)

((bufferdata)->size)

Referenced by npyiter_coalesce_axes(), NpyIter_EnableExternalLoop(), NpyIter_GetIndexPtr(), and NpyIter_GotoIndex().

#define NBF_STRIDES

(

bufferdata

)

Value:

( \
        &(bufferdata)->bd_flexdata + 0)

Referenced by NpyIter_GotoIndex().

#define NBF_WRITETRANSFERDATA

(

bufferdata

)

Value:

((NpyAuxData **) \
        (&(bufferdata)->bd_flexdata + 7*(nop)))

Referenced by NpyIter_Copy().

#define NBF_WRITETRANSFERFN

(

bufferdata

)

Value:

((PyArray_StridedTransferFn **) \
        (&(bufferdata)->bd_flexdata + 6*(nop)))

#define NIT_ADVANCE_AXISDATA	(		axisdata,
			count
	)		axisdata = NIT_INDEX_AXISDATA(axisdata, count)

Referenced by npyiter_flip_negative_strides().

#define NIT_AXISDATA

(

iter

)

Value:

((NpyIter_AxisData *)( \
        &(iter)->iter_flexdata + NIT_AXISDATA_OFFSET(itflags, ndim, nop)))

Referenced by npyiter_flip_negative_strides(), and NpyIter_GetIndexPtr().

#define NIT_AXISDATA_OFFSET	(		itflags,
			ndim,
			nop
	)

Value:

(NIT_BUFFERDATA_OFFSET(itflags, ndim, nop) + \
         NIT_BUFFERDATA_SIZEOF(itflags, ndim, nop))

#define NIT_AXISDATA_SIZEOF	(		itflags,
			ndim,
			nop
	)

Value:

(( \ \
        1 + \ \
        1 + \ \
        2*((nop)+1) \
        )*NPY_SIZEOF_INTP )

Size of one AXISDATA struct within the iterator

Referenced by npyiter_flip_negative_strides().

#define NIT_BASEOFFSETS

(

iter

)

Value:

((npy_intp *)( \
        &(iter)->iter_flexdata + NIT_BASEOFFSETS_OFFSET(itflags, ndim, nop)))

Referenced by NpyIter_GetAxisStrideArray().

#define NIT_BASEOFFSETS_OFFSET	(		itflags,
			ndim,
			nop
	)

Value:

(NIT_RESETDATAPTR_OFFSET(itflags, ndim, nop) + \
         NIT_RESETDATAPTR_SIZEOF(itflags, ndim, nop))

#define NIT_BASEOFFSETS_SIZEOF	(		itflags,
			ndim,
			nop
	)		((NPY_SIZEOF_INTP)*(nop+1))

#define NIT_BUFFERDATA

(

iter

)

Value:

((NpyIter_BufferData *)( \
        &(iter)->iter_flexdata + NIT_BUFFERDATA_OFFSET(itflags, ndim, nop)))

Referenced by NpyIter_Copy(), NpyIter_EnableExternalLoop(), NpyIter_GetBufferSize(), NpyIter_GetIndexPtr(), and NpyIter_GotoIndex().

#define NIT_BUFFERDATA_OFFSET	(		itflags,
			ndim,
			nop
	)

Value:

(NIT_OPITFLAGS_OFFSET(itflags, ndim, nop) + \
         NIT_OPITFLAGS_SIZEOF(itflags, ndim, nop))

#define NIT_BUFFERDATA_SIZEOF	(		itflags,
			ndim,
			nop
	)		((itflags&NPY_ITFLAG_BUFFER) ? ((NPY_SIZEOF_INTP)*(6 + 9*nop)) : 0)

#define NIT_DTYPES

(

iter

)

Value:

((PyArray_Descr **)( \
        &(iter)->iter_flexdata + NIT_DTYPES_OFFSET(itflags, ndim, nop)))

Referenced by NpyIter_Copy().

#define NIT_DTYPES_OFFSET	(		itflags,
			ndim,
			nop
	)

Value:

(NIT_PERM_OFFSET() + \
         NIT_PERM_SIZEOF(itflags, ndim, nop))

#define NIT_DTYPES_SIZEOF	(		itflags,
			ndim,
			nop
	)		((NPY_SIZEOF_INTP)*(nop))

#define NIT_INDEX_AXISDATA	(		axisdata,
			index
	)

Value:

((NpyIter_AxisData *) \
        (((char *)(axisdata)) + (index)*sizeof_axisdata))

Macro to advance an AXISDATA pointer by a specified count. Requires that sizeof_axisdata be previously initialized to NIT_AXISDATA_SIZEOF(itflags, ndim, nop).

#define NIT_ITEREND

(

iter

)

(iter->iterend)

Referenced by NpyIter_EnableExternalLoop(), and NpyIter_HasDelayedBufAlloc().

#define NIT_ITERINDEX

(

iter

)

(iter->iterindex)

Referenced by NpyIter_EnableExternalLoop(), NpyIter_GotoIndex(), and NpyIter_New().

#define NIT_ITERSIZE

(

iter

)

(iter->itersize)

#define NIT_ITERSTART

(

iter

)

(iter->iterstart)

Referenced by NpyIter_EnableExternalLoop(), and NpyIter_HasDelayedBufAlloc().

#define NIT_ITFLAGS

(

iter

)

((iter)->itflags)

Internal-only ITERATOR DATA MEMBER ACCESS

Referenced by NpyIter_Copy(), NpyIter_EnableExternalLoop(), npyiter_flip_negative_strides(), NpyIter_GetIndexPtr(), NpyIter_GetIterIndex(), NpyIter_HasMultiIndex(), and NpyIter_IsGrowInner().

#define NIT_MASKOP

(

iter

)

((iter)->maskop)

#define NIT_NDIM

(

iter

)

((iter)->ndim)

Referenced by npyiter_flip_negative_strides(), and NpyIter_HasMultiIndex().

#define NIT_NOP

(

iter

)

((iter)->nop)

Referenced by NpyIter_Copy(), NpyIter_EnableExternalLoop(), npyiter_flip_negative_strides(), NpyIter_GetDataPtrArray(), NpyIter_GetIndexPtr(), NpyIter_GetIterIndexRange(), NpyIter_GetShape(), NpyIter_HasMultiIndex(), and NpyIter_IsGrowInner().

#define NIT_OPERANDS

(

iter

)

Value:

((PyArrayObject **)( \
        &(iter)->iter_flexdata + NIT_OPERANDS_OFFSET(itflags, ndim, nop)))

Referenced by NpyIter_Copy(), and NpyIter_GetShape().

#define NIT_OPERANDS_OFFSET	(		itflags,
			ndim,
			nop
	)

Value:

(NIT_BASEOFFSETS_OFFSET(itflags, ndim, nop) + \
         NIT_BASEOFFSETS_SIZEOF(itflags, ndim, nop))

#define NIT_OPERANDS_SIZEOF	(		itflags,
			ndim,
			nop
	)		((NPY_SIZEOF_INTP)*(nop))

#define NIT_OPITFLAGS

(

iter

)

Value:

( \
        &(iter)->iter_flexdata + NIT_OPITFLAGS_OFFSET(itflags, ndim, nop))

Referenced by NpyIter_GetDataPtrArray().

#define NIT_OPITFLAGS_OFFSET	(		itflags,
			ndim,
			nop
	)

Value:

(NIT_OPERANDS_OFFSET(itflags, ndim, nop) + \
         NIT_OPERANDS_SIZEOF(itflags, ndim, nop))

#define NIT_OPITFLAGS_SIZEOF	(		itflags,
			ndim,
			nop
	)		(NPY_INTP_ALIGNED(nop))

#define NIT_PERM

(

iter

)

Value:

((npy_int8 *)( \
        &(iter)->iter_flexdata + NIT_PERM_OFFSET()))

Referenced by npyiter_flip_negative_strides().

#define NIT_PERM_OFFSET

(

)

(0)

Byte offsets of the iterator members starting from iter->iter_flexdata

#define NIT_PERM_SIZEOF	(		itflags,
			ndim,
			nop
	)		NPY_INTP_ALIGNED(NPY_MAXDIMS)

Byte sizes of the iterator members

#define NIT_RESETDATAPTR

(

iter

)

Value:

((char **)( \
        &(iter)->iter_flexdata + NIT_RESETDATAPTR_OFFSET(itflags, ndim, nop)))

Referenced by NpyIter_GetIterIndexRange().

#define NIT_RESETDATAPTR_OFFSET	(		itflags,
			ndim,
			nop
	)

Value:

(NIT_DTYPES_OFFSET(itflags, ndim, nop) + \
         NIT_DTYPES_SIZEOF(itflags, ndim, nop))

#define NIT_RESETDATAPTR_SIZEOF	(		itflags,
			ndim,
			nop
	)		((NPY_SIZEOF_INTP)*(nop+1))

#define NIT_SIZEOF_ITERATOR	(		itflags,
			ndim,
			nop
	)

Value:

( \
        sizeof(struct NpyIter_InternalOnly) + \
        NIT_AXISDATA_OFFSET(itflags, ndim, nop) + \
        NIT_AXISDATA_SIZEOF(itflags, ndim, nop)*(ndim))

Size of the whole iterator

#define NPY_INTP_ALIGNED

(

size

)

((size + 0x7)&(-0x8))

System Message: ERROR/3 (<string>, line 1) Document or section may not begin with a transition.

---

System Message: ERROR/3 (<string>, line 1) Document may not end with a transition.

Rounds up a number of bytes to be divisible by sizeof intp

#define NPY_IT_CONSTRUCTION_TIMING   0

**** ITERATOR CONSTRUCTION TIMING *********

#define NPY_IT_DBG_PRINT

(

s

)

Referenced by npyiter_apply_forced_iteration_order().

#define NPY_IT_DBG_PRINT1	(		s,
			p1
	)

Referenced by npyiter_coalesce_axes(), and npyiter_copy_to_buffers().

#define NPY_IT_DBG_PRINT2	(		s,
			p1,
			p2
	)

Referenced by npyiter_coalesce_axes().

#define NPY_IT_DBG_PRINT3	(		s,
			p1,
			p2,
			p3
	)

Referenced by npyiter_flip_negative_strides().

#define NPY_IT_DBG_TRACING   0

System Message: ERROR/3 (<string>, line 1) Document or section may not begin with a transition.

---

System Message: ERROR/3 (<string>, line 1) Document may not end with a transition.

**** PRINTF DEBUG TRACING *********

#define NPY_IT_TIME_POINT

(

var

)

#define NPY_ITFLAG_BUFFER   0x0080

The iterator is buffered

#define NPY_ITFLAG_DELAYBUF   0x0400

Delay buffer allocation until first Reset* call

Referenced by NpyIter_EnableExternalLoop().

#define NPY_ITFLAG_EXLOOP   0x0020

The inner loop is handled outside the iterator

#define NPY_ITFLAG_FORCEDORDER   0x0010

The iteration order was forced on construction

#define NPY_ITFLAG_GROWINNER   0x0100

The iterator should grow the buffered inner loop when possible

#define NPY_ITFLAG_HASINDEX   0x0004

The iterator is tracking an index

#define NPY_ITFLAG_HASMULTIINDEX   0x0008

The iterator is tracking a multi-index

#define NPY_ITFLAG_IDENTPERM   0x0001

Internal iterator flags

The perm is the identity

#define NPY_ITFLAG_NEEDSAPI   0x0800

Iteration needs API access during iternext

#define NPY_ITFLAG_NEGPERM   0x0002

The perm has negative entries (indicating flipped axes)

#define NPY_ITFLAG_ONEITERATION   0x0200

There is just one iteration, can specialize iternext for that

#define NPY_ITFLAG_RANGE   0x0040

The iterator is ranged

#define NPY_ITFLAG_REDUCE   0x1000

Iteration includes one or more operands being reduced

Referenced by NpyIter_GotoIndex().

#define NPY_ITFLAG_REUSE_REDUCE_LOOPS   0x2000

Reduce iteration doesn't need to recalculate reduce loops next time

#define NPY_NO_DEPRECATED_API

#define NPY_OP_ITFLAG_ALIGNED   0x10

The operand is aligned

#define NPY_OP_ITFLAG_BUFNEVER   0x08

The operand never needs buffering

#define NPY_OP_ITFLAG_CAST   0x04

The operand needs type conversion/byte swapping/alignment

#define NPY_OP_ITFLAG_READ   0x02

The operand will be read from

#define NPY_OP_ITFLAG_REDUCE   0x20

The operand is being reduced

#define NPY_OP_ITFLAG_VIRTUAL   0x40

The operand is for temporary use, does not have a backing array

#define NPY_OP_ITFLAG_WRITE   0x01

Internal iterator per-operand iterator flags

The operand will be written to

Referenced by NpyIter_GetDataPtrArray().

#define NPY_OP_ITFLAG_WRITEMASKED   0x80

The operand requires masking when copying buffer -> array

Referenced by npyiter_coalesce_axes().

#define PY_SSIZE_T_CLEAN

---

Typedef Documentation

typedef struct NpyIter_AD NpyIter_AxisData

typedef struct NpyIter_BD NpyIter_BufferData

---

Function Documentation

NPY_NO_EXPORT int npyiter_allocate_buffers	(	NpyIter *	iter,
		char **	errmsg
	)

If errmsg is non-NULL, it should point to a variable which will receive the error message, and no Python exception will be set. This is so that the function can be called from code not holding the GIL.

npy_uint32 itflags = NIT_ITFLAGS(iter);

int ndim = NIT_NDIM(iter);

If we have determined that a buffer may be needed, allocate one.

Referenced by NpyIter_EnableExternalLoop().

NPY_NO_EXPORT void npyiter_coalesce_axes

(

NpyIter *

iter

)

Internal helper functions shared between implementation files

The HASMULTIINDEX or IDENTPERM flags do not apply after coalescing

Check that all the axes can be coalesced

If the number of axes shrunk, reset the perm and compress the data into the new layout.

Reset to an identity perm

References NAD_INDEX, NAD_SHAPE, NAD_STRIDES, NBF_REDUCE_OUTERSIZE, NBF_SIZE, NPY_IT_DBG_PRINT1, NPY_IT_DBG_PRINT2, NPY_OP_ITFLAG_WRITEMASKED, and PyArray_TransferMaskedStridedToNDim().

NPY_NO_EXPORT void npyiter_copy_from_buffers

(

NpyIter *

iter

)

This gets called after the the buffers have been exhausted, and their data needs to be written back to the arrays. The multi-index must be positioned for the beginning of the buffer.

If we're past the end, nothing to copy

Copy the data back to the arrays. If the type has refs, this function moves them so the buffer's refs are released.

Copy back only if the pointer was pointing to the buffer

If this operand is being reduced in the inner loop, its buffering stride was set to zero, and just one element was copied.

The mask pointer may be in the buffer or in the array, detect which one.

If there's no copy back, we may have to decrement refs. In this case, the transfer function has a 'decsrcref' transfer function, so we can use it to do the decrement.

Decrement refs only if the pointer was pointing to the buffer

Decrement refs

Zero out the memory for safety. For instance, if during iteration some Python code copied an array pointing into the buffer, it will get None values for its references after this.

Referenced by NpyIter_EnableExternalLoop(), and NpyIter_GotoIndex().

NPY_NO_EXPORT void npyiter_copy_to_buffers	(	NpyIter *	iter,
		char **	prev_dataptrs
	)

This gets called after the iterator has been positioned to a multi-index for the start of a buffer. It decides which operands need a buffer, and copies the data into the buffers.

Have to get this flag before npyiter_checkreducesize sets it for the next iteration.

Calculate the size if using any buffers

If last time around, the reduce loop structure was full, we reuse it

Try to do make the outersize as big as possible. This allows it to shrink when processing the last bit of the outer reduce loop, then grow again at the beginnning of the next outer reduce loop.

If the full transfer size doesn't fit in the buffer, truncate it

If there are any reduction operands, we may have to make the size smaller so we don't copy the same value into a buffer twice, as the buffering does not have a mechanism to combine values itself.

Calculate the maximum size if using a single stride and no buffers

If the buffer is write-only, these two are NULL, and the buffer pointers will be set up but the read copy won't be done

Never need to buffer this operand

Should not adjust the stride - ad_strides[iop] could be zero, but strides[iop] was initialized to the first non-trivial stride.

Never need to buffer this operand

Should not adjust the stride - ad_strides[iop] could be zero, but strides[iop] was initialized to the first non-trivial stride.

Just a copy

No copyswap or cast was requested, so all we're doing is copying the data to fill the buffer and produce a single stride. If the underlying data already does that, no need to copy it.

If some other op is reduced, we have a double reduce loop

In this case, the buffer is being used

Just a copy, but with a reduction

It's all in one stride in the inner loop dimension

It's all in one stride in the reduce outer loop

Outer reduce loop advances by one item

In this case, the buffer is being used

Both outer and inner reduce loops have stride 0

Outer reduce loop advances by one item

It's all in one stride in the reduce outer loop

Outer reduce loop advances by one item

In this case, the buffer is being used

Reduction in outer reduce loop

Advance to next items in outer reduce loop

In this case, the buffer is always being used

The buffer is being used with reduction

Both outer and inner reduce loops have stride 0

Outer reduce loop advances by one item

Reduction in outer reduce loop

Advance to next items in outer reduce loop

If stransfer wasn't set to NULL, buffering is required

If this operand is being reduced in the inner loop, set its buffering stride to zero, and just copy one element.

When we're reducing a single element, and it's still the same element, don't overwrite it even when reuse reduce loops is unset. This preserves the precision of the intermediate calculation.

If the whole buffered loop structure remains the same, and the source pointer for this data didn't change, we don't have to copy the data again.

If the data type requires zero-inititialization

Can't skip the transfer in this case

If the data type requires zero-inititialization

If buffering wasn't needed, we can grow the inner loop to as large as possible.

TODO: Could grow REDUCE loop too with some more logic above.

References _PyArray_Descr::elsize, and NPY_IT_DBG_PRINT1.

Referenced by NpyIter_EnableExternalLoop(), NpyIter_GotoIndex(), and NpyIter_New().

NPY_NO_EXPORT void npyiter_goto_iterindex	(	NpyIter *	iter,
		npy_intp	iterindex
	)

This sets the AXISDATA portion of the iterator to the specified iterindex, updating the pointers as well. This function does no error checking.

Set the multi-index, from the fastest-changing to the slowest-changing.

Accumulate the successive pointers with their offsets in the opposite order, starting from the original data pointers.

Referenced by NpyIter_EnableExternalLoop(), NpyIter_GotoIndex(), and NpyIter_New().