From 30cf60561f769976a540db5f170813db0c9c2677 Mon Sep 17 00:00:00 2001
From: Toby Jaffey <toby@ringtailsoftware.co.uk>
Date: Sun, 7 Dec 2025 01:00:52 +0000
Subject: [PATCH] Fibonacci sample

---
 apps/fib/Makefile | 27 ++++++++++++++++++++++++++
 apps/fib/fib.c    | 48 +++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 75 insertions(+)
 create mode 100644 apps/fib/Makefile
 create mode 100644 apps/fib/fib.c

diff --git a/apps/fib/Makefile b/apps/fib/Makefile
new file mode 100644
index 0000000..6e39a11
--- /dev/null
+++ b/apps/fib/Makefile
@@ -0,0 +1,27 @@
+PROJECT:=fib
+
+DOCKER_IMAGE=riscv-dev
+DOCKER_CMD:=docker run --rm -v ${PWD}../../../:/data -w /data/apps/${PROJECT} ${DOCKER_IMAGE}
+PREFIX:=${DOCKER_CMD} riscv64-unknown-elf-
+CFLAGS+=-I../../common
+CFLAGS+=-fno-stack-protector
+CFLAGS+=-static-libgcc -fdata-sections -ffunction-sections
+CFLAGS+=-g -Os -march=rv32ima_zicsr -mabi=ilp32 -static
+LDFLAGS:= -T ../linker.ld -nostdlib -Wl,--gc-sections
+LIBS:= #-lgcc # needed for softfp
+
+SRCS=${PROJECT}.c ../crt0.s
+
+all:
+	${PREFIX}gcc -o ${PROJECT}.elf ${CFLAGS} ${LDFLAGS} ${SRCS} ${LIBS}
+	$(PREFIX)objcopy ${PROJECT}.elf -O binary ${PROJECT}.bin
+
+disasm: all
+	$(PREFIX)objdump -S -d -f ${PROJECT}.elf
+
+test: all
+	../../host/host ${PWD}/${PROJECT}.bin
+
+clean:
+	rm -f ${PROJECT}.o ${PROJECT}.elf ${PROJECT}.bin
+
diff --git a/apps/fib/fib.c b/apps/fib/fib.c
new file mode 100644
index 0000000..064eb4d
--- /dev/null
+++ b/apps/fib/fib.c
@@ -0,0 +1,48 @@
+#define USE_MAIN
+#include "uvm32_target.h"
+
+// print n terms of fibonacci series
+void printFib(int n) {
+    int prev1 = 1;
+    int prev2 = 0;
+
+    for (int i = 1; i <= n; i++) {
+        if (i > 2) {
+            int curr = prev1 + prev2;
+            prev2 = prev1;
+            prev1 = curr;
+            printd(curr);
+        } else if (i == 1) {
+            printd(prev2);
+        } else if (i == 2) {
+            printd(prev1);
+        }
+    }
+}
+
+// print n terms of fibonacci series, recursively
+void fib_recursive(int n, int prev1, int prev2) {
+    if (n < 3) {
+        return;
+    }
+    
+    int curr = prev1 + prev2;
+    printd(curr);
+  
+    return fib_recursive(n - 1, prev2, curr);
+}
+
+void printFibRec(int n) {
+    printd(0);
+    printd(1);
+    fib_recursive(n, 0, 1);
+}
+
+void main(void) {
+    int n = 40;
+    println("fib() loop");
+    printFib(n);
+    println("fib() recursive");
+    printFibRec(n);
+}
+