CyberShake BBP Integration

This page details the process of integrating CyberShake with the Broadband Platform. The goals of this integration are both to enable CyberShake to produce stochastic high-frequency seismograms as a complement to deterministic low-frequency seismograms, and also to avoid having to repeat the same integration process we went through for CyberShake 1.4 and CyberShake Study 15.12 every time we want to use the BBP stochastic codes.

Approach

We have identified the following BBP executables, or elements, which are needed in CyberShake:

• srf2stoch (C)
• hb_high (Fortran)
• wcc_getpeak (C)
• wcc_siteamp14 (C)
• wcc_tfilter (C)
• wcc_resamp_arbdt (C)
• wcc_add (C)
• integ_diff (C)

As part of the BBP, each of these pieces of code contains a main() function, which typically works as follows:

main() {
  // Parse command-line parameters
  // Open and read input files into input data structure
  // Execute science kernel, populating output data structure
  // Open and write output files from output data structure
}

For CyberShake, we would like to be able to use the science kernels of the BBP elements, but provide CyberShake-specific parameters, pass data structures around in memory between multiple elements, and read from and write to different data formats. To accomplish this, we propose extracting the science kernels from the main() functions and creating subroutines with them, separating the I/O from the scientific calculations. Following this approach, a revised main method would contain:

main() {
  // Open and read input files into input data structure
  science_kernel_subroutine(command-line arguments, input_data_structure, output_data_structure)
  // Open and write output files from output data structure
}

Then, in the CyberShake codebase, we would use this function as follows:

// Open and read input files into input data structure
// Allocate memory for output data structure
// Create parameter string with CyberShake-specific parameters for getpar to parse
science_kernel_subroutine(parameter_string, input_data_structure, output_data_structure)
// Do additional processing with output data structure
// Open and write output data structure to file

The intent is that these changes would be pushed out to the BBP codebase and also to Rob Graves, so that future revisions work from this refactored version and are straightforward to integrate with CyberShake.

Example

As an example, below we show the proposed modifications for wcc_getpeak.

Change	Original code	Modified code
Subroutine prototype		float wcc_getpeak(int param_string_len, char** param_string, float* seis, struct statdata* head1);
Extract science kernel into subroutine	int main(ac,av) { ... float max = -1.0e+20; float min = 1.0e+20; int inbin = 0; int outbin = 0; int keepsign = 0; float scale = 1.0; ... s1 = NULL; s1 = read_wccseis(infile,&head1,s1,inbin); for(i=0;i<head1.nt;i++)  {  if(s1[i] > max)   max = s1[i];  if(s1[i] < min)   min = s1[i];  } ...	... s1 = NULL; s1 = read_wccseis(infile,&head1,s1,inbin); float peak = wcc_getpeak(ac, av, s1, head1); printf("%10.2f %13.5e %s\n",head1.edist,peak,head1.stat); } float wcc_getpeak(int param_string_len, char** param_string, float* s1, struct statdata* head1) {  float max = -1.0e+20;  float min = 1.0e+20;  int keepsign = 0;  float scale = 1.0; ...  for(i=0;i<head1->nt;i++)   {   if(s1[i] > max)    max = s1[i];   if(s1[i] < min)    min = s1[i];   }  ...
Relocate parsing of non-I/O parameters to subroutine	int main(ac,av) { ... sprintf(infile,"stdin"); setpar(ac,av); getpar("infile","s",infile); getpar("inbin","d",&inbin); getpar("keepsign","d",&keepsign); getpar("scale","f",&scale); endpar(); s1 = NULL; s1 = read_wccseis(infile,&head1,s1,inbin); ...	float wcc_getpeak(int param_string_len, char** param_string, float* s1, struct statdata* head1) {  float max = -1.0e+20;  float min = 1.0e+20;  int keepsign = 0;  float scale = 1.0;  setpar(param_string_len, param_string);  getpar("keepsign","d",&keepsign);  getpar("scale","f",&scale);  endpar();  for(i=0;i<head1->nt;i++) ...

Here is possible CyberShake code which could use this modified code:

...
float* seis = malloc(nt*sizeof(float));
fread(fp_in, sizeof(float), nt, seis);
struct statdata head1;
head1.nt = nt;
char** param_string = NULL;
float peak = wcc_getpeak(param_string, 0, seis, &head1);
...
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