include example.c

5 files changed, 39 insertions, 2 deletions

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 5b42932..464a411 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -201,3 +201,8 @@ jobs:
       working-directory: ./c
     - run: BLAKE3_NO_SSE2=1 BLAKE3_NO_SSE41=1 BLAKE3_NO_AVX2=1 BLAKE3_NO_AVX512=1 make -f Makefile.testing test_asm
       working-directory: ./c
+    # Restore the files we deleted above.
+    - run: git checkout .
+    # Build the example.
+    - run: make -f Makefile.testing example
+      working-directory: ./c
diff --git a/c/.gitignore b/c/.gitignore
index c7a8b28..0bf608c 100644
--- a/c/.gitignore
+++ b/c/.gitignore
@@ -1,2 +1,3 @@
 blake3
+example
 *.o
diff --git a/c/Makefile.testing b/c/Makefile.testing
index b4db5c8..41e6b82 100644
--- a/c/Makefile.testing
+++ b/c/Makefile.testing
@@ -71,5 +71,8 @@ test_asm: CFLAGS += -DBLAKE3_TESTING -fsanitize=address,undefined
 test_asm: asm
 	./test.py
 
+example: example.c blake3.c blake3_dispatch.c blake3_portable.c $(ASM_TARGETS)
+	$(CC) $(CFLAGS) $(EXTRAFLAGS) $^ -o $@ $(LDFLAGS)
+
 clean: 
 	rm -f $(NAME) *.o
diff --git a/c/README.md b/c/README.md
index 6211243..5e8b4e6 100644
--- a/c/README.md
+++ b/c/README.md
@@ -35,8 +35,9 @@ int main() {
 }
 ```
 
-If you save the example code above as `example.c`, and you're on x86\_64
-with a Unix-like OS, you can compile a working binary like this:
+The code above is included in this directory as `example.c`. If you're
+on x86\_64 with a Unix-like OS, you can compile a working binary like
+this:
 
 ```bash
 gcc -O3 -o example example.c blake3.c blake3_dispatch.c blake3_portable.c \
diff --git a/c/example.c b/c/example.c
new file mode 100644
index 0000000..02fe3c3
--- /dev/null
+++ b/c/example.c
@@ -0,0 +1,27 @@
+#include "blake3.h"
+#include <stdio.h>
+#include <unistd.h>
+
+int main() {
+  // Initialize the hasher.
+  blake3_hasher hasher;
+  blake3_hasher_init(&hasher);
+
+  // Read input bytes from stdin.
+  unsigned char buf[65536];
+  ssize_t n;
+  while ((n = read(STDIN_FILENO, buf, sizeof(buf))) > 0) {
+    blake3_hasher_update(&hasher, buf, n);
+  }
+
+  // Finalize the hash. BLAKE3_OUT_LEN is the default output length, 32 bytes.
+  uint8_t output[BLAKE3_OUT_LEN];
+  blake3_hasher_finalize(&hasher, output, BLAKE3_OUT_LEN);
+
+  // Print the hash as hexadecimal.
+  for (size_t i = 0; i < BLAKE3_OUT_LEN; i++) {
+    printf("%02x", output[i]);
+  }
+  printf("\n");
+  return 0;
+}