Changed 'order' to 'layout' in cspan md.

Neigher the 'C' / 'F' convension from python, nor left / right from std::mdspan are great names => changed to c_ROWMAJOR / c_COLMAJOR like in matlab.

4 files changed, 28 insertions, 19 deletions

diff --git a/docs/cspan_api.md b/docs/cspan_api.md
index 39b97473..c3556dc3 100644
--- a/docs/cspan_api.md
+++ b/docs/cspan_api.md
@@ -44,12 +44,15 @@ SpanTypeN_iter  SpanType_begin(const SpanTypeN* self);
 SpanTypeN_iter  SpanType_end(const SpanTypeN* self);
 void            SpanType_next(SpanTypeN_iter* it);
 
-SpanTypeN       cspan_md(ValueType* data, d1, d2, ...);                   // make a multi-dim cspan, row-major order.
-SpanTypeN       cspan_md_order(char order, ValueType* data, d1, d2, ...); // order='C': row-major, 'F': column-major (FORTRAN).
+                // make a multi-dim cspan
+SpanTypeN       cspan_md(ValueType* data, d1, d2, ...); // row-major
+SpanTypeN       cspan_md_layout(cspan_layout layout, ValueType* data, d1, d2, ...);
 
-                // transpose a md span (inverse axes). No changes to the underlying array.
+                // transpose a md span. Inverses layout and axes only.
 void            cspan_transpose(const SpanTypeN* self);
-bool            cspan_is_order_F(const SpanTypeN* self);
+cspan_layout    cspan_get_layout(const SpanTypeN* self);
+bool            cspan_is_rowmajor(const SpanTypeN* self);
+bool            cspan_is_colmajor(const SpanTypeN* self);
 
                 // create a subspan of input span rank. Like e.g. cspan_slice(Span3, &ms3, {off,off+count}, {c_ALL}, {c_ALL});
 SpanType        cspan_subspan(const SpanType* span, intptr_t offset, intptr_t count);
@@ -70,8 +73,9 @@ OutSpanN        cspan_slice(TYPE OutSpanN, const SpanTypeM* parent, {x0,x1}, {y0
 |:------------------|:----------------------------------------------------|:---------------------|
 | SpanTypeN         | `struct { ValueType *data; uint32_t shape[N]; .. }` | SpanType with rank N |
 | SpanTypeN`_value` | `ValueType`                                         | The ValueType        |
-| `c_ALL`           | Use with `cspan_slice()`.                           | Full extent          |
-| `c_END`           |            "                                        | End of extent        |
+| `c_ALL`           | `cspan_slice(&md, {1,3}, {c_ALL})`                  | Full extent          |
+| `c_END`           | `cspan_slice(&md, {1,c_END}, {2,c_END})`            | End of extent        |
+| `cspan_layout`    | `enum { c_ROWMAJOR, c_COLMAJOR }`                   | Multi-dim layout     |
 
 ## Example 1
 
@@ -182,7 +186,7 @@ void print_span(myspan2 ms) {
 int main(void) {
     int arr[] = {1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24};
 
-    myspan3 ms3 = cspan_md_order('C', arr, 2, 3, 4); // row-major ('F' column-major)
+    myspan3 ms3 = cspan_md(arr, 2, 3, 4); // row-major layout
     myspan3 ss3 = cspan_slice(myspan3, &ms3, {c_ALL}, {0,3}, {2,c_END});
     myspan2 a = cspan_submd3(&ss3, 1);
     myspan2 b = a;
diff --git a/include/stc/cspan.h b/include/stc/cspan.h
index 6f8de8ec..f9f3b02a 100644
--- a/include/stc/cspan.h
+++ b/include/stc/cspan.h
@@ -98,7 +98,7 @@ int demo2() {
     } \
     STC_INLINE void Self##_next(Self##_iter* it) { \
         int i, inc, done; \
-        if (it->_s->stride.d[0] < it->_s->stride.d[RANK - 1]) i=0, inc=1; else i=RANK-1, inc=-1; \
+        if (cspan_is_colmajor(it->_s)) i=0, inc=1; else i=RANK-1, inc=-1; \
         it->ref += _cspan_next##RANK(it->pos, it->_s->shape, it->_s->stride.d, RANK, i, inc, &done); \
         if (done) it->ref = NULL; \
     } \
@@ -115,6 +115,7 @@ using_cspan_tuple(7); using_cspan_tuple(8);
 
 #define c_END -1
 #define c_ALL 0,c_END
+typedef enum {c_ROWMAJOR, c_COLMAJOR} cspan_layout;
 
 /* Use cspan_init() for static initialization only. c_init() for non-static init. */
 #define cspan_init(SpanType, ...) \
@@ -132,7 +133,9 @@ using_cspan_tuple(7); using_cspan_tuple(8);
 
 #define cspan_size(self) _cspan_size((self)->shape, cspan_rank(self))
 #define cspan_rank(self) c_arraylen((self)->shape)
-#define cspan_is_order_F(self) ((self)->stride.d[0] < (self)->stride.d[cspan_rank(self) - 1])
+#define cspan_is_colmajor(self) ((self)->stride.d[0] < (self)->stride.d[cspan_rank(self) - 1])
+#define cspan_is_rowmajor(self) (!cspan_is_colmajor(self))
+#define cspan_get_layout(self) (cspan_is_colmajor(self) ? c_COLMAJOR : c_ROWMAJOR)
 #define cspan_index(self, ...) c_PASTE(cspan_idx_, c_NUMARGS(__VA_ARGS__))(self, __VA_ARGS__)
 #define cspan_at(self, ...) ((self)->data + cspan_index(self, __VA_ARGS__))
 #define cspan_front(self) ((self)->data)
@@ -165,10 +168,10 @@ using_cspan_tuple(7); using_cspan_tuple(8);
 #define cspan_submd4_4(self, x, y, z) \
     {.data=cspan_at(self, x, y, z, 0), .shape={(self)->shape[3]}, .stride=(cspan_tuple1){.d={(self)->stride.d[3]}}}
 
-#define cspan_md(array, ...) cspan_md_order('C', array, __VA_ARGS__)
-#define cspan_md_order(order, array, ...) /* order='C' or 'F' */ \
+#define cspan_md(array, ...) cspan_md_layout(c_ROWMAJOR, array, __VA_ARGS__)
+#define cspan_md_layout(layout, array, ...) \
     {.data=array, .shape={__VA_ARGS__}, \
-     .stride=*(c_PASTE(cspan_tuple, c_NUMARGS(__VA_ARGS__))*)_cspan_shape2stride(order, ((int32_t[]){__VA_ARGS__}), c_NUMARGS(__VA_ARGS__))}
+     .stride=*(c_PASTE(cspan_tuple, c_NUMARGS(__VA_ARGS__))*)_cspan_shape2stride(layout, ((int32_t[]){__VA_ARGS__}), c_NUMARGS(__VA_ARGS__))}
 
 #define cspan_transpose(self) \
     _cspan_transpose((self)->shape, (self)->stride.d, cspan_rank(self))
@@ -225,7 +228,7 @@ STC_INLINE intptr_t _cspan_idxN(int rank, const int32_t shape[], const int32_t s
 }
 
 STC_API intptr_t _cspan_next2(int32_t pos[], const int32_t shape[], const int32_t stride[], int rank, int i, int inc, int* done);
-#define _cspan_next1(pos, shape, stride, rank, i, inc, done) (*done = ++pos[0]==shape[0], stride[0])
+#define _cspan_next1(pos, shape, stride, rank, i, inc, done) (*done = ++pos[0]==shape[0], (void)(i|inc), stride[0])
 #define _cspan_next3 _cspan_next2
 #define _cspan_next4 _cspan_next2
 #define _cspan_next5 _cspan_next2
@@ -237,7 +240,7 @@ STC_API intptr_t _cspan_slice(int32_t oshape[], int32_t ostride[], int* orank,
                               const int32_t shape[], const int32_t stride[],
                               int rank, const int32_t a[][2]);
 
-STC_API int32_t* _cspan_shape2stride(char order, int32_t shape[], int rank);
+STC_API int32_t* _cspan_shape2stride(cspan_layout layout, int32_t shape[], int rank);
 #endif // STC_CSPAN_H_INCLUDED
 
 /* --------------------- IMPLEMENTATION --------------------- */
@@ -246,6 +249,7 @@ STC_API int32_t* _cspan_shape2stride(char order, int32_t shape[], int rank);
 STC_DEF intptr_t _cspan_next2(int32_t pos[], const int32_t shape[], const int32_t stride[], int rank, int i, int inc, int* done) {
     intptr_t off = stride[i];
     ++pos[i];
+
     while (--rank && pos[i] == shape[i]) {
         pos[i] = 0; ++pos[i + inc];
         off += stride[i + inc] - stride[i]*shape[i];
@@ -255,9 +259,9 @@ STC_DEF intptr_t _cspan_next2(int32_t pos[], const int32_t shape[], const int32_
     return off;
 }
 
-STC_DEF int32_t* _cspan_shape2stride(char order, int32_t shape[], int rank) {
+STC_DEF int32_t* _cspan_shape2stride(cspan_layout layout, int32_t shape[], int rank) {
     int i, inc;
-    if (order == 'F') i = 0, inc = 1;
+    if (layout == c_COLMAJOR) i = 0, inc = 1;
     else i = rank - 1, inc = -1;
     int32_t k = 1, s1 = shape[i], s2;
 
@@ -277,6 +281,7 @@ STC_DEF intptr_t _cspan_slice(int32_t oshape[], int32_t ostride[], int* orank,
     intptr_t off = 0;
     int i = 0, oi = 0;
     int32_t end;
+
     for (; i < rank; ++i) {
         off += stride[i]*a[i][0];
         switch (a[i][1]) {
diff --git a/misc/examples/spans/matmult.c b/misc/examples/spans/matmult.c
index 35dad7a9..266fa121 100644
--- a/misc/examples/spans/matmult.c
+++ b/misc/examples/spans/matmult.c
@@ -70,8 +70,8 @@ int main(void)
       Values_push(&values, (crandf() - 0.5)*4.0);
 
   double out[D1*D2];
-  Mat3 data = cspan_md_order('C', values.data, N, D1, D2);
-  OutMat c = cspan_md_order('C', out, D1, D2);
+  Mat3 data = cspan_md_layout(c_ROWMAJOR, values.data, N, D1, D2);
+  OutMat c = cspan_md_layout(c_ROWMAJOR, out, D1, D2);
   Mat2 a = cspan_submd3(&data, 0);
   double sum = 0.0;
   clock_t t = clock();
diff --git a/misc/examples/spans/mdspan.c b/misc/examples/spans/mdspan.c
index db601850..630ffddb 100644
--- a/misc/examples/spans/mdspan.c
+++ b/misc/examples/spans/mdspan.c
@@ -9,7 +9,7 @@ int main(void) {
     double* data = c_new_n(double, nx*ny*nz);
 
     printf("\nMultidim span ms[5, 4, 3], fortran ordered");
-    DSpan3 ms = cspan_md_order('F', data, nx, ny, nz); // Fortran, not 'C'
+    DSpan3 ms = cspan_md_layout(c_COLMAJOR, data, nx, ny, nz);
 
     int idx = 0;
     for (int i = 0; i < ms.shape[0]; ++i)