Add some rudimentary error and debug handling

src/c-kzg.h

@@ -20,16 +20,14 @@
 typedef enum {
     C_KZG_SUCCESS = 0,
     C_KZG_BADARGS,
-    c_KZG_ERROR,
+    C_KZG_ERROR,
 } C_KZG_RET;
 
 #include <stdbool.h>
 #include "../inc/blst.h"
 
-#define DEBUG
-
-#include <assert.h>
 #ifdef DEBUG
+#include <assert.h>
 #include <stdio.h>
 #define ASSERT(cond, ret) if (!(cond)) \
         { \

src/fft_fr_test.c

@@ -41,7 +41,8 @@ const uint64_t inv_fft_expected[][4] =
 void compare_sft_fft(void) {
     // Initialise: ascending values of i (could be anything), and arbitrary size
     unsigned int size = 12;
-    FFTSettings fs = new_fft_settings(size);
+    FFTSettings fs;
+    TEST_CHECK(new_fft_settings(&fs, size) == C_KZG_SUCCESS);
     blst_fr data[fs.max_width], out0[fs.max_width], out1[fs.max_width];
     for (int i = 0; i < fs.max_width; i++) {
         fr_from_uint64(data + i, i);
@@ -62,7 +63,8 @@ void compare_sft_fft(void) {
 void roundtrip_fft(void) {
     // Initialise: ascending values of i, and arbitrary size
     unsigned int size = 12;
-    FFTSettings fs = new_fft_settings(size);
+    FFTSettings fs;
+    TEST_CHECK(new_fft_settings(&fs, size) == C_KZG_SUCCESS);
     blst_fr data[fs.max_width], coeffs[fs.max_width];
     for (int i = 0; i < fs.max_width; i++) {
         fr_from_uint64(data + i, i);
@@ -84,7 +86,8 @@ void roundtrip_fft(void) {
 
 void inverse_fft(void) {
     // Initialise: ascending values of i
-    FFTSettings fs = new_fft_settings(4);
+    FFTSettings fs;
+    TEST_CHECK(new_fft_settings(&fs, 4) == C_KZG_SUCCESS);
     blst_fr data[fs.max_width], out[fs.max_width];
     for (int i = 0; i < fs.max_width; i++) {
         fr_from_uint64(&data[i], i);

src/fft_g1_test.c

@@ -59,7 +59,8 @@ void p1_sub_works(void) {
 void compare_sft_fft(void) {
     // Initialise: arbitrary size
     unsigned int size = 6;
-    FFTSettings fs = new_fft_settings(size);
+    FFTSettings fs;
+    TEST_CHECK(new_fft_settings(&fs, size) == C_KZG_SUCCESS);
     blst_p1 data[fs.max_width], slow[fs.max_width], fast[fs.max_width];
     make_data(data, fs.max_width);
     
@@ -78,7 +79,8 @@ void compare_sft_fft(void) {
 void roundtrip_fft(void) {
     // Initialise: arbitrary size
     unsigned int size = 10;
-    FFTSettings fs = new_fft_settings(size);
+    FFTSettings fs;
+    TEST_CHECK(new_fft_settings(&fs, size) == C_KZG_SUCCESS);
     blst_p1 expected[fs.max_width], data[fs.max_width], coeffs[fs.max_width];
     make_data(expected, fs.max_width);
     make_data(data, fs.max_width);

src/fft_util.c

@@ -31,41 +31,42 @@ void fr_from_uint64(blst_fr *a, uint64_t n) {
     blst_fr_from_uint64(a, vals);
 }
 
-// Returns an array of powers of the root of unity
-// Allocates space for the array that needs to be freed later
-blst_fr *expand_root_of_unity(blst_fr *root_of_unity, uint64_t width) {
-    blst_fr *roots = malloc((width + 1) * sizeof(blst_fr));
+// Create an array of powers of the root of unity
+// The `out` array must be of size `width + 1`
+C_KZG_RET expand_root_of_unity(blst_fr *roots, blst_fr *root_of_unity, uint64_t width) {
     roots[0] = one;
     roots[1] = *root_of_unity;
 
     for (int i = 2; !is_one(&roots[i - 1]); i++) {
-        //ASSERT(i <= width, C_KZG_ERROR);
-        assert(i <= width);
+        ASSERT(i <= width, C_KZG_ERROR);
         blst_fr_mul(&roots[i], &roots[i - 1], root_of_unity);
     }
-    assert(is_one(&roots[width]));
+    ASSERT(is_one(&roots[width]), C_KZG_ERROR);
 
-    return roots;
+    return C_KZG_SUCCESS;
 }
 
-// Return a reversed copy of the list of Fr provided
-// `width` is one less than the length of `r`
-// Allocates space for the array that needs to be freed later
-blst_fr *reverse(blst_fr *r, uint64_t width) {
-   blst_fr *rr = malloc((width + 1) * sizeof(blst_fr));
+// Create a reversed list of Fr provided
+// `width` is one less than the length of `roots`
+C_KZG_RET reverse(blst_fr *out, blst_fr *roots, uint64_t width) {
    for (int i = 0; i <= width; i++) {
-       rr[i] = r[width - i];
-   }
-   return rr;
+       out[i] = roots[width - i];
    }
 
-FFTSettings new_fft_settings(unsigned int max_scale) {
-    FFTSettings s;
-    s.max_width = (uint64_t)1 << max_scale;
-    blst_fr_from_uint64(&s.root_of_unity, scale2_root_of_unity[max_scale]);
-    s.expanded_roots_of_unity = expand_root_of_unity(&s.root_of_unity, s.max_width);
-    s.reverse_roots_of_unity = reverse(s.expanded_roots_of_unity, s.max_width);
-    return s;
+   return C_KZG_SUCCESS;
+}
+
+C_KZG_RET new_fft_settings(FFTSettings *s, unsigned int max_scale) {
+    C_KZG_RET ret;
+    s->max_width = (uint64_t)1 << max_scale;
+    blst_fr_from_uint64(&s->root_of_unity, scale2_root_of_unity[max_scale]);
+    s->expanded_roots_of_unity = malloc((s->max_width + 1) * sizeof(blst_fr));
+    s->reverse_roots_of_unity = malloc((s->max_width + 1) * sizeof(blst_fr));
+
+    ret = expand_root_of_unity(s->expanded_roots_of_unity, &s->root_of_unity, s->max_width);
+    if (ret != C_KZG_SUCCESS) return ret;
+    ret = reverse(s->reverse_roots_of_unity, s->expanded_roots_of_unity, s->max_width);
+    return ret;
 }
 
 void free_fft_settings(FFTSettings *s) {

src/fft_util.h

@@ -72,7 +72,7 @@ typedef struct {
 bool is_one(const blst_fr *fr_p);
 bool is_power_of_two(uint64_t n);
 void fr_from_uint64(blst_fr *a, uint64_t n);
-blst_fr *expand_root_of_unity(blst_fr *root_of_unity, uint64_t width);
-blst_fr *reverse(blst_fr *r, uint64_t width);
-FFTSettings new_fft_settings(unsigned int max_scale);
+C_KZG_RET expand_root_of_unity(blst_fr * roots, blst_fr *root_of_unity, uint64_t width);
+C_KZG_RET reverse(blst_fr *out, blst_fr *roots, uint64_t width);
+C_KZG_RET new_fft_settings(FFTSettings *s, unsigned int max_scale);
 void free_fft_settings(FFTSettings *s);

src/fft_util_test.c

@@ -43,8 +43,8 @@ void roots_of_unity_are_plausible(void) {
 
 void reverse_works(void) {
     int n = 24;
-    blst_fr arr[n + 1];
-    blst_fr *rev, diff;
+    blst_fr arr[n + 1], rev[n + 1];
+    blst_fr diff;
 
     // Initialise - increasing values
     arr[0] = one;
@@ -53,7 +53,7 @@ void reverse_works(void) {
     }
 
     // Reverse
-    rev = reverse(arr, n);
+    TEST_CHECK(reverse(rev, arr, n) == C_KZG_SUCCESS);
 
     // Verify - decreasing values
     for (int i = 0; i < n; i++) {
@@ -61,19 +61,17 @@ void reverse_works(void) {
         TEST_CHECK(true == is_one(&diff));
     }
     TEST_CHECK(true == is_one(rev + n));
-
-    free(rev);
 }
 
 void expand_roots_is_plausible(void) {
     // Just test one (largeish) value of scale
-    unsigned int scale = 20;
+    unsigned int scale = 15;
     unsigned int width = 1 << scale;
-    blst_fr root, *expanded, prod;
+    blst_fr root, expanded[width + 1], prod;
 
     // Initialise
     blst_fr_from_uint64(&root, scale2_root_of_unity[scale]);
-    expanded = expand_root_of_unity(&root, width);
+    TEST_CHECK(expand_root_of_unity(expanded, &root, width) == C_KZG_SUCCESS);
 
     // Verify - each pair should multiply to one
     TEST_CHECK(true == is_one(expanded + 0));
@@ -82,8 +80,6 @@ void expand_roots_is_plausible(void) {
         blst_fr_mul(&prod, expanded + i, expanded + width - i);
         TEST_CHECK(true == is_one(&prod));
     }
-
-    free(expanded);
 }
 
 void new_fft_settings_is_plausible(void) {
@@ -91,7 +87,9 @@ void new_fft_settings_is_plausible(void) {
     unsigned int scale = 21;
     unsigned int width = 1 << scale;
     blst_fr prod;
-    FFTSettings s = new_fft_settings(scale);
+    FFTSettings s;
+
+    TEST_CHECK(new_fft_settings(&s, scale) == C_KZG_SUCCESS);
 
     // Verify - each pair should multiply to one
     for (unsigned int i = 1; i <= width; i++) {