check size and alignment of struct members

test-blend-bGPDstroke.c

/*
 * test alignments of struct members
 * run on multiple platforms to compare output

 cc test-blend-bGPDstroke.c -o testpad
 ./testpad
*/

#include <stdio.h>
#include <stddef.h>

// copied from DNA_gpencil_types.h e5b788bad8bc
struct bGPDspoint;
struct bGPDtriangle;

typedef struct bGPDstroke_Runtime {
  /** runtime final colors (result of original colors and modifiers) */
  float tmp_stroke_rgba[4];

  /** runtime final fill colors (result of original colors and modifiers) */
  float tmp_fill_rgba[4];

  /** temporary layer name only used during copy/paste to put the stroke in the original layer */
  char tmp_layerinfo[128];

  /** Runtime falloff factor (only for transform). */
  float multi_frame_falloff;
  char _pad[4];

  /** Original stroke (used to dereference evaluated data) */
  struct bGPDstroke *gps_orig;
} bGPDstroke_Runtime;

typedef struct bGPDstroke {
  struct bGPDstroke *next, *prev;

  /** Array of data-points for stroke. */
  struct bGPDspoint *points;
  /** Tessellated triangles for GP Fill. */
  struct bGPDtriangle *triangles;
  /** Number of data-points in array. */
  int totpoints;
  /** Number of triangles in array. */
  int tot_triangles;

  /** Thickness of stroke. */
  short thickness;
  /** Various settings about this stroke. */
  short flag, _pad[2];

  /** Init time of stroke. */
  double inittime;

  /** Color name. */
  char colorname[128];

  /** Material index. */
  int mat_nr;
  /** Caps mode for each stroke extreme */
  short caps[2];

  /** gradient control along y for color */
  float gradient_f;
  /** factor xy of shape for dots gradients */
  float gradient_s[2];
  char _pad_3[4];

  /** Vertex weight data. */
  struct MDeformVert *dvert;
  void *_pad3;

  struct bGPDstroke_Runtime runtime;
} bGPDstroke;


int main(int argc, char ** argv)
{
    printf("sizeof char - %lu\n",sizeof(char));
    printf("sizeof short - %lu\n",sizeof(short));
    printf("sizeof int - %lu\n",sizeof(int));
    printf("sizeof long - %lu\n",sizeof(long));
    printf("sizeof long long - %lu\n",sizeof(long long));
    printf("sizeof float - %lu\n",sizeof(float));
    printf("sizeof double - %lu\n",sizeof(double));
    printf("sizeof long double - %lu\n",sizeof(long double));
    printf("sizeof void* - %lu\n",sizeof(void*));
    printf("sizeof size_t - %lu\n",sizeof(size_t));

    printf("\nOffsets:\n");
    printf("next=%ld;\n", (long) offsetof(bGPDstroke, next));
    printf("prev=%ld;\n", (long) offsetof(bGPDstroke, prev));
    printf("points=%ld;\n", (long) offsetof(bGPDstroke, points));
    printf("triangles=%ld;\n", (long) offsetof(bGPDstroke, triangles));
    printf("totpoints=%ld;\n", (long) offsetof(bGPDstroke, totpoints));
    printf("tot_triangles=%ld;\n", (long) offsetof(bGPDstroke, tot_triangles));
    printf("thickness=%ld;\n", (long) offsetof(bGPDstroke, thickness));
    printf("flag=%ld;\n", (long) offsetof(bGPDstroke, flag));
    printf("_pad=%ld;\n", (long) offsetof(bGPDstroke, _pad));
    printf("inittime=%ld;\n", (long) offsetof(bGPDstroke, inittime));
    printf("colorname=%ld;\n", (long) offsetof(bGPDstroke, colorname));
    printf("mat_nr=%ld;\n", (long) offsetof(bGPDstroke, mat_nr));
    printf("caps=%ld;\n", (long) offsetof(bGPDstroke, caps));
    printf("gradient_f=%ld;\n", (long) offsetof(bGPDstroke, gradient_f));
    printf("gradient_s=%ld;\n", (long) offsetof(bGPDstroke, gradient_s));
    printf("_pad_3=%ld;\n", (long) offsetof(bGPDstroke, _pad_3));
    printf("dvert=%ld;\n", (long) offsetof(bGPDstroke, dvert));
    printf("_pad3=%ld;\n", (long) offsetof(bGPDstroke, _pad3));
    printf("runtime=%ld;\n", (long) offsetof(bGPDstroke, runtime));

    printf("sizeof(bGPDstroke)=%ld\n", (long) sizeof(bGPDstroke));

    // exit cleanly if we get here
    return 0;
}