binding with ffi bam_merge_core

gistfile1.rb

          # @abstract    Merge multiple sorted BAM.
          # @param  is_by_qname whether to sort by query name
          # @param  out  output BAM file name
          # @param  headers  name of SAM file from which to copy '@' header lines,
          #                  or NULL to copy them from the first file to be merged
          # @param  n    number of files to be merged
          # @param  fn   names of files to be merged
          # 
          # @discussion Padding information may NOT correctly maintained. This
          # function is NOT thread safe.
          # int bam_merge_core(int by_qname, const char *out, const char *headers, int n, char * const *fn,
          #           int flag, const char *reg)

          attach_function :bam_merge_core, [:int, :string, :string, :int, :pointer, :int, :string], :int
          def self.bam_merge(bam_output_file_name, bam_array_input_file_names)
            is_by_qname = 0
            headers = 0
            flag = 0
            reg = 0
            ary = bam_array_input_file_names.map do |filename|
              FFI::MemoryPointer.from_string(filename)
            end
            fns=FFI::MemoryPointer.new :pointer, ary.size
            fns.put_array_of_pointer 0, ary
            bam_merge_core(is_by_qname, bam_output_file_name, headers, bam_array_input_file_names.size, fns, flag, reg)
          end 

gistfile1.txt

          # @abstract    Merge multiple sorted BAM.
          # @param  is_by_qname whether to sort by query name
          # @param  out  output BAM file name
          # @param  headers  name of SAM file from which to copy '@' header lines,
          #                  or NULL to copy them from the first file to be merged
          # @param  n    number of files to be merged
          # @param  fn   names of files to be merged
          # 
          # @discussion Padding information may NOT correctly maintained. This
          # function is NOT thread safe.
          # int bam_merge_core(int by_qname, const char *out, const char *headers, int n, char * const *fn,
          #           int flag, const char *reg)

          attach_function :bam_merge_core, [:int, :string, :string, :int, :pointer, :int, :string], :int
          def self.bam_merge(bam_output_file_name, bam_array_input_file_names)
            is_by_qname = 0
            headers = 0
            flag = 0
            reg = 0
            ary = bam_array_input_file_names.map do |filename|
              FFI::MemoryPointer.from_string(filename)
            end
            fns=FFI::MemoryPointer.new :pointer, ary.size
            fns.put_array_of_pointer 0, ary
            bam_merge_core(is_by_qname, bam_output_file_name, headers, bam_array_input_file_names.size, fns, flag, reg)
          end