3ec039397b40eaa784d02994512b9bc5d69ae1c8
braney
  Sun Jun 11 15:50:34 2017 -0700
ongoing work on hgComposite

diff --git src/hg/lib/mathWig.c src/hg/lib/mathWig.c
index 18e3bd1..b596b33 100644
--- src/hg/lib/mathWig.c
+++ src/hg/lib/mathWig.c
@@ -1,111 +1,120 @@
 /* Copyright (C) 2017 The Regents of the University of California 
  * See README in this or parent directory for licensing information. */
 
 #include "common.h"
 #include "bigWig.h"
 
 // stack of arithmetic operators
 struct opcodeStack
     {
     int depth;
     int maxDepth;
     char *stack;
     };
 
 static boolean pushOpcode(struct opcodeStack *opcodeStack, char *word)
 /* Check to see if word is operator, if so, push it onto the stack */
 {
 boolean ret = FALSE;
 
 if (strlen(word) > 1)
     return FALSE;
 
 switch(*word)
     {
     case '+':
     case '*':
     case '-':
     case '/':
         if (opcodeStack->depth == opcodeStack->maxDepth)
             {
             opcodeStack->maxDepth += 10;
             opcodeStack->stack = realloc(opcodeStack->stack, opcodeStack->maxDepth);
             }
         opcodeStack->stack[opcodeStack->depth] = *word;
         opcodeStack->depth++;
         ret =  TRUE;
         break;
     }
 
 return ret;
 }
 
 double *mathWigGetValues(char *equation, char *chrom, unsigned winStart, unsigned winEnd)
 /* Build an array of doubles that is calculated from bigWig's listed
  * in equation in the requested region. */
 {
+static char lastOpcode = 0;
 char *words[100];
 int count = chopByWhite(equation, words, sizeof(words)/sizeof(char *));
 int jj,ii;
 unsigned width = winEnd - winStart;
 struct lm *lm = lmInit(0);
 double *data = needHugeMem(width * sizeof(double));
 bzero(data, width * sizeof(double));
 struct opcodeStack opcodeStack;
 bzero(&opcodeStack, sizeof opcodeStack);
 
 boolean firstTime = TRUE;
 for (jj=0; jj < count; jj++)
     {
     if (pushOpcode(&opcodeStack, words[jj]))
         continue;
     struct bbiFile *bwf = bigWigFileOpen(words[jj]);
 
     struct bbiInterval *iv, *ivList = bigWigIntervalQuery(bwf, chrom, winStart, winEnd, lm);
 
     if (firstTime)
         {
         for (iv = ivList; iv != NULL; iv = iv->next)
             {
             unsigned start = max(0, iv->start - winStart);
             unsigned end = min(width, iv->end - winStart);
 
             for (ii = start; ii < end; ii++)
                 data[ii] = iv->val;
             }
 
         firstTime = FALSE;
         }
     else
         {
+        char opcode;
         if (opcodeStack.depth == 0)
-            errAbort("underflow in opcode stack");
-        char opcode = opcodeStack.stack[--opcodeStack.depth];
+            {
+            opcode = lastOpcode;
+            if (opcode == 0)
+                opcode = '+';
+
+            //errAbort("underflow in opcode stack");
+            }
+        else
+            lastOpcode = opcode = opcodeStack.stack[--opcodeStack.depth];
         for (iv = ivList; iv != NULL; iv = iv->next)
             {
             unsigned start = max(0, iv->start - winStart);
             unsigned end = min(width, iv->end - winStart);
             for (ii = start; ii < end; ii++)
                 {
                 switch(opcode)
                     {
                     case '+':
                         data[ii] += iv->val;
                         break;
                     case '-':
                         data[ii] -= iv->val;
                         break;
                     case '*':
                         data[ii] *= iv->val;
                         break;
                     case '/':
                         data[ii] /= iv->val;
                         break;
                     }
                 }
             }
         }
     }
 
 return data;
 }