| CROSS-PLATFORM PORTABILITY GUIDELINES FOR GALLIUM3D |
| |
| |
| = General Considerations = |
| |
| The frontend and winsys driver support a rather limited number of |
| platforms. However, the pipe drivers are meant to run in a wide number of |
| platforms. Hence the pipe drivers, the auxiliary modules, and all public |
| headers in general, should strictly follow these guidelines to ensure |
| |
| |
| = Compiler Support = |
| |
| * Include the p_compiler.h. |
| |
| * Cast explicitly when converting to integer types of smaller sizes. |
| |
| * Cast explicitly when converting between float, double and integral types. |
| |
| * Don't use named struct initializers. |
| |
| * Don't use variable number of macro arguments. Use static inline functions |
| instead. |
| |
| * Don't use C99 features. |
| |
| = Standard Library = |
| |
| * Avoid including standard library headers. Most standard library functions are |
| not available in Windows Kernel Mode. Use the appropriate p_*.h include. |
| |
| == Memory Allocation == |
| |
| * Use MALLOC, CALLOC, FREE instead of the malloc, calloc, free functions. |
| |
| * Use align_pointer() function defined in u_memory.h for aligning pointers |
| in a portable way. |
| |
| == Debugging == |
| |
| * Use the functions/macros in p_debug.h. |
| |
| * Don't include assert.h, call abort, printf, etc. |
| |
| |
| = Code Style = |
| |
| == Inherantice in C == |
| |
| The main thing we do is mimic inheritance by structure containment. |
| |
| Here's a silly made-up example: |
| |
| /* base class */ |
| struct buffer |
| { |
| int size; |
| void (*validate)(struct buffer *buf); |
| }; |
| |
| /* sub-class of bufffer */ |
| struct texture_buffer |
| { |
| struct buffer base; /* the base class, MUST COME FIRST! */ |
| int format; |
| int width, height; |
| }; |
| |
| |
| Then, we'll typically have cast-wrapper functions to convert base-class |
| pointers to sub-class pointers where needed: |
| |
| static inline struct vertex_buffer *vertex_buffer(struct buffer *buf) |
| { |
| return (struct vertex_buffer *) buf; |
| } |
| |
| |
| To create/init a sub-classed object: |
| |
| struct buffer *create_texture_buffer(int w, int h, int format) |
| { |
| struct texture_buffer *t = malloc(sizeof(*t)); |
| t->format = format; |
| t->width = w; |
| t->height = h; |
| t->base.size = w * h; |
| t->base.validate = tex_validate; |
| return &t->base; |
| } |
| |
| Example sub-class method: |
| |
| void tex_validate(struct buffer *buf) |
| { |
| struct texture_buffer *tb = texture_buffer(buf); |
| assert(tb->format); |
| assert(tb->width); |
| assert(tb->height); |
| } |
| |
| |
| Note that we typically do not use typedefs to make "class names"; we use |
| 'struct whatever' everywhere. |
| |
| Gallium's pipe_context and the subclassed psb_context, etc are prime examples |
| of this. There's also many examples in Mesa and the Mesa state tracker. |