feat: Implement comparisons

2 files changed, 92 insertions, 0 deletions

diff --git a/BigInt.c b/BigInt.c
index 21c22d3..1e1a0db 100644
--- a/BigInt.c
+++ b/BigInt.c
@@ -565,3 +565,88 @@ B_tostr(MemoryManager *mm, BigInt intx) {
     mm->free(*mm, (void**)&bcd);
     return str;
 }
+
+int
+B_eq(const BigInt intx, const BigInt inty) {
+    if (NULL == intx || NULL == inty)
+        return intx == inty;
+
+    struct BigIntMeta *xm = B_metadata(intx), *ym = B_metadata(inty);
+    UWord *x = intx, *y = inty;
+
+    usize words;
+    if (xm->words < ym->words) {
+        for (usize w = xm->words; w < ym->words; ++w)
+            if (y[w] != 0)
+                return 0;
+
+        words = xm->words;
+    }
+    else {
+        for (usize w = ym->words; w < xm->words; ++w)
+            if (x[w] != 0)
+                return 0;
+
+        words = ym->words;
+    }
+
+    for (usize w = words - 1; w < words; --w)
+        if (x[w] != y[w])
+            return 0;
+
+    return 1;
+}
+
+int
+B_not_eq(const BigInt x, const BigInt y) {
+    return !B_eq(x, y);
+}
+
+int
+B_lt(const BigInt intx, const BigInt inty) {
+    if (NULL == intx || NULL == inty)
+        return R_NullArgument;
+
+    struct BigIntMeta *xm = B_metadata(intx), *ym = B_metadata(inty);
+    UWord *x = (void*)intx, *y = (void*)inty;
+
+    usize words;
+    if (xm->words < ym->words) {
+        for (usize w = xm->words; w < ym->words; ++w)
+            if (y[w] != 0)
+                return 1;
+
+        words = xm->words;
+    }
+    else {
+        for (usize w = ym->words; w < xm->words; ++w)
+            if (x[w] != 0)
+                return 0;
+
+        words = ym->words;
+    }
+
+    for (usize w = words - 1; w < words; --w) {
+        if (x[w] < y[w])
+            return 1;
+        else if (x[w] > y[w])
+            return 0;
+    }
+
+    return 0;
+}
+
+int
+B_le(const BigInt x, const BigInt y) {
+    return B_lt(x, y) || B_eq(x, y);
+}
+
+int
+B_gt(const BigInt x, const BigInt y) {
+    return !B_lt(x, y) && !B_eq(x, y);
+}
+
+int
+B_ge(const BigInt x, const BigInt y) {
+    return !B_lt(x, y);
+}
diff --git a/BigInt.h b/BigInt.h
index d894b35..89cb3ab 100644
--- a/BigInt.h
+++ b/BigInt.h
@@ -37,4 +37,11 @@ usize B_bytes(BigInt x);
 usize B_bitwidth(BigInt x);
 char* B_tostr(MemoryManager *mm, BigInt x);
 
+int B_eq(const BigInt x, const BigInt y);
+int B_not_eq(const BigInt x, const BigInt y);
+int B_lt(const BigInt x, const BigInt y);
+int B_le(const BigInt x, const BigInt y);
+int B_gt(const BigInt x, const BigInt y);
+int B_ge(const BigInt x, const BigInt y);
+
 #endif /* _BIGINT */