1 files changed, 32 insertions, 0 deletions
diff --git a/src/libbiguint/bu_divmod.c b/src/libbiguint/bu_divmod.c
new file mode 100644
index 0000000..5d5802f
--- /dev/null
+++ b/src/libbiguint/bu_divmod.c
@@ -0,0 +1,32 @@
+/* ISC license. */
+
+#include <errno.h>
+#include <skalibs/uint32.h>
+#include <skalibs/biguint.h>
+
+/*
+   q = y/x mod m.
+*/
+
+int bu_divmod (uint32 *q, unsigned int qn, uint32 const *y, unsigned int yn, uint32 const *x, unsigned int xn, uint32 const *m, unsigned int mn)
+{
+  unsigned int ylen = bu_len(y, yn) ;
+  unsigned int xlen = bu_len(x, xn) ;
+  unsigned int mlen = bu_len(m, mn) ;
+  unsigned int n = ylen ;
+  if (n < xlen) n = xlen ;
+  if (n < mlen) n = mlen ;
+  if (!n) return (errno = EDOM, 0) ;
+  {
+    uint32 yy[n] ;
+    uint32 xx[n] ;
+    uint32 mm[n] ;
+    bu_gcd(xx, n, x, xlen, m, mlen) ;
+    if ((xx[0] != 1) || (bu_len(xx, n) != 1)) return (errno = EDOM, 0) ;
+    bu_copy_internal(yy, y, ylen) ; bu_zero(yy+ylen, n-ylen) ;
+    bu_copy_internal(xx, x, xlen) ; bu_zero(xx+xlen, n-xlen) ;
+    bu_copy_internal(mm, m, mlen) ; bu_zero(mm+mlen, n-mlen) ;
+    bu_divmod_internal(yy, xx, mm, n) ;
+    return bu_copy(q, qn, yy, n) ;
+  }
+}