initial upload

src/bigmath/chain/segment.cpp

@@ -0,0 +1,79 @@
+#include "segment.hpp"
+
+#include <sstream>
+#include <iomanip>
+
+namespace bigmath {
+
+    const dlen_t segment::digit_count = 128;
+    const dlen_t segment::byte_count = segment::digit_count / 2;
+
+    segment::segment() {
+        digits = new dlen_t[byte_count]{};
+    }
+
+    segment::~segment() {
+        delete[] digits;
+    }
+
+    d10_t segment::operator[](dlen_t i) const {
+        dlen_t j = i >> 1;
+        dlen_t k = (i & 1) * 4;
+        d10_t  b = digits[j];
+        return (b >> k) & 0xFu;
+    }
+
+    void segment::set(dlen_t i, d10_t n) {
+        dlen_t j = i >> 1;
+        dlen_t k = (i & 1) * 4;
+        d10_t  b = digits[j];
+        b &= 0xF0u >> k;
+        n &= 0xFu;
+        digits[j] = b | (n << k);
+    }
+
+    const digits_t segment::bytes() const {
+        return digits;
+    }
+
+    std::string segment::describe() const {
+        std::ostringstream out;
+
+        // We'll iterate backwards
+        size_t i = digit_count;
+        u32 use_space = 0;
+        while (i > 0) {
+            d10_t val = operator[](i - 1);
+
+            // Count repetitions
+            size_t count = 1;
+            while (i > count && operator[](i - count - 1) == val) ++count;
+
+            // temporal string
+            std::ostringstream one;
+            one << u32(val);
+            auto str = one.str();
+
+            // Decide whether to compress
+            if (count > 5) {
+                if(use_space) out << " ";
+                out << "[" << str << " x " << count << "]";
+                use_space = 4;
+            } else {
+                for (size_t j = 0; j < count; ++j) {
+                    if(use_space > 3) {
+                        out << " ";
+                        use_space = 1;
+                    }
+                    use_space++;
+                    out << str;
+                }
+            }
+
+            i -= count;
+        }
+
+        return out.str();
+    }
+
+}