feat(c-miner): port miner pipeline to modular C implementation

utils.h

@@ -0,0 +1,37 @@
+#ifndef UTILS_H
+#define UTILS_H
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include "config.h"
+
+typedef struct {
+    char *data;
+    size_t len;
+    size_t cap;
+} StrBuf;
+
+void sb_init(StrBuf *sb);
+void sb_free(StrBuf *sb);
+int sb_reserve(StrBuf *sb, size_t extra);
+int sb_append(StrBuf *sb, const char *s);
+int sb_append_n(StrBuf *sb, const char *s, size_t n);
+int sb_append_byte_hex(StrBuf *sb, uint8_t b);
+char *sb_take(StrBuf *sb);
+
+int hex_char_to_val(char c);
+int hex_to_bytes(const char *hex, uint8_t **out, size_t *out_len);
+char *bytes_to_hex(const uint8_t *data, size_t len);
+int hex_to_fixed_bytes(const char *hex, uint8_t *out, size_t out_len);
+void reverse_bytes(uint8_t *data, size_t n);
+
+void double_sha256(const uint8_t *data, size_t len, uint8_t out[32]);
+int encode_varint_hex(uint64_t value, StrBuf *sb);
+
+char *decode_nbits_hex(uint32_t nbits);
+char *calculate_target_hex(const char *bits_hex, double difficulty_factor, const char *network);
+
+char *hex_add_width(const char *base_hex, int add_value);
+
+#endif