test(fft): add C example to verify FFT IP

sdk/software/examples/fft/Makefile

@@ -0,0 +1,11 @@
+TARGET = fft
+
+CFLAGS += -O3 -g
+
+C_SRCS := $(wildcard ./*.c )
+
+OBJDIR = obj
+COMMON_DIR = ../../bsp
+GCC_DIR=../../../toolchains/loongson-gnu-toolchain-8.3-x86_64-loongarch32r-linux-gnusf-v2.0
+PICOLIBC_DIR=../../../toolchains/picolibc
+include ../../bsp/common.mk

sdk/software/examples/fft/main.c

@@ -0,0 +1,178 @@
+#include <stdio.h> 
+#include <string.h>
+#include <math.h>
+#include <common_func.h>
+#include <confreg_time.h>
+
+// BSP板级支持包所需全局变量
+unsigned long UART_BASE = 0xbf000000;
+unsigned long CONFREG_TIMER_BASE = 0xbf20f100;
+unsigned long CONFREG_CLOCKS_PER_SEC = 50000000L;
+unsigned long CORE_CLOCKS_PER_SEC = 33000000L;
+
+#define FFT_BASE          0xbf400000
+#define FFT_IN_RE_BASE    (FFT_BASE + 0x1000)
+#define FFT_IN_IM_BASE    (FFT_BASE + 0x2000)
+#define FFT_OUT_RE_BASE   (FFT_BASE + 0x3000)
+#define FFT_OUT_IM_BASE   (FFT_BASE + 0x4000)
+#define FFT_CSR_REG       (FFT_BASE + 0xF000)
+#define FFT_CTRL_START    (1 << 4)
+#define FFT_STAT_DONE     (1 << 1)
+#define FFT_STAT_BUSY     (1 << 0)
+#define FFT_POINT_NUM     1024
+
+#define DMA_BASE          0xbf300000
+#define DMA_CTRL          (DMA_BASE + 0x0000)
+#define DMA_LEN           (DMA_BASE + 0x0004)
+#define DMA_SRC_ADDR      (DMA_BASE + 0x0008)
+#define DMA_DST_ADDR      (DMA_BASE + 0x000c)
+#define DMA_STATUS        (DMA_BASE + 0x0010)
+
+const float PI = 3.14159265358979323846;
+
+// 读取定时器的当前Tick
+unsigned int get_timer_ticks() {
+    return RegRead(CONFREG_TIMER_BASE);
+}
+
+// ---------------------------------------------------------
+// 软件FFT实现 (基2 DIT-FFT 算法)
+// ---------------------------------------------------------
+void sw_fft(float re[], float im[], int n) {
+    int i, j, k, l;
+    float tr, ti, ur, ui, wr, wi;
+
+    // 1. 比特翻转 (Bit Reversal)
+    j = 0;
+    for (i = 0; i < n - 1; i++) {
+        if (i < j) {
+            tr = re[i]; ti = im[i];
+            re[i] = re[j]; im[i] = im[j];
+            re[j] = tr; im[j] = ti;
+        }
+        k = n / 2;
+        while (k <= j) {
+            j -= k;
+            k /= 2;
+        }
+        j += k;
+    }
+
+    // 2. 蝶形运算 (Butterfly Computation)
+    for (l = 1; l < n; l *= 2) {
+        ur = 1.0; 
+        ui = 0.0;
+        wr = cos(PI / l);
+        wi = -sin(PI / l);
+        
+        for (i = 0; i < n; i += 2 * l) {
+            ur = 1.0; 
+            ui = 0.0;
+            for (j = 0; j < l; j++) {
+                int p = i + j;
+                int q = p + l;
+                
+                tr = re[q] * ur - im[q] * ui;
+                ti = re[q] * ui + im[q] * ur;
+                
+                re[q] = re[p] - tr;
+                im[q] = im[p] - ti;
+                re[p] += tr;
+                im[p] += ti;
+                
+                float next_ur = ur * wr - ui * wi;
+                ui = ur * wi + ui * wr;
+                ur = next_ur;
+            }
+        }
+    }
+}
+
+int main(int argc, char** argv)
+{
+    unsigned int fft_csr = RegRead(FFT_CSR_REG);
+    printf("fft_csr = %x\n", fft_csr);
+
+    // 准备测试数据
+    float sw_in_re[FFT_POINT_NUM];
+    float sw_in_im[FFT_POINT_NUM];
+
+    for (int i = 0; i < FFT_POINT_NUM; i++) {
+        float dc_part   = 4000.0f;
+        float f10_part  = 8000.0f * cos(2 * PI * 10.0 * i / FFT_POINT_NUM);
+        float f200_part = 6000.0f * sin(2 * PI * 200.0 * i / FFT_POINT_NUM);
+        float f400_part = 3000.0f * sin(2 * PI * 400.0 * i / FFT_POINT_NUM);
+        
+        sw_in_re[i] = dc_part + f10_part + f200_part + f400_part;
+        sw_in_im[i] = 0.0f;
+    }
+
+    unsigned int tick_start, tick_end;
+    unsigned int hw_time, sw_time;
+
+    // ==========================================
+    // 1. 硬件加速 FFT 测试
+    // ==========================================
+    printf("\n--- Starting Hardware FFT ---\n");
+    tick_start = get_ns();
+
+    for (int i = 0; i < FFT_POINT_NUM; i++) {
+        RegWrite(FFT_IN_RE_BASE + (i * 4), (unsigned int)((int)sw_in_re[i]));
+        RegWrite(FFT_IN_IM_BASE + (i * 4), 0);
+    }
+    
+    
+    RegWrite(FFT_CSR_REG, FFT_CTRL_START);
+    while ((RegRead(FFT_CSR_REG) & FFT_STAT_DONE) == 0) {
+        // 等待硬件计算完成
+    }
+    
+    tick_end = get_ns();
+    
+    // 如果定时器是递减的，这里可能是 tick_start - tick_end
+    // 假设定时器是向上递增的：
+    hw_time = tick_end - tick_start;  
+
+    int hw_out_re[FFT_POINT_NUM];
+    int hw_out_im[FFT_POINT_NUM];
+    for (int i = 0; i < FFT_POINT_NUM; i++) {
+        hw_out_re[i] = (int)RegRead(FFT_OUT_RE_BASE + (i * 4));
+        hw_out_im[i] = (int)RegRead(FFT_OUT_IM_BASE + (i * 4));
+    }
+
+    // ==========================================
+    // 2. 纯软件 FFT 测试
+    // ==========================================
+    printf("--- Starting Software FFT ---\n");
+    tick_start = get_ns();
+    
+    sw_fft(sw_in_re, sw_in_im, FFT_POINT_NUM);
+    
+    tick_end = get_ns();
+    sw_time = tick_end - tick_start;
+
+
+    // ==========================================
+    // 3. 打印对比结果
+    // ==========================================
+    printf("\n--- Performance Comparison ---\n");
+    printf("Timer Clock Freq : %lu Hz\n", CONFREG_CLOCKS_PER_SEC);
+    printf("Hardware FFT Time: %u ns (%.3f ms)\n", hw_time, (float)hw_time / 1000000.0);
+    printf("Software FFT Time: %u ns (%.3f ms)\n", sw_time, (float)sw_time / 1000000.0);
+    
+    if (hw_time > 0) {
+        printf("Speedup Ratio    : %.2fx\n", (float)sw_time / hw_time);
+    }
+
+    printf("\n--- Verification (Only showing Bins with energy > 10) ---\n");
+    for (int i = 0; i < FFT_POINT_NUM; i++) {
+        if (fabs(hw_out_re[i]) > 10 || fabs(hw_out_im[i]) > 10) {
+            printf("Bin [%4d] Hz: HW(Re:%6d, Im:%6d) | SW(Re:%6d, Im:%6d)\n", 
+                    i, 
+                    hw_out_re[i], hw_out_im[i], 
+                    (int)sw_in_re[i] / FFT_POINT_NUM, (int)sw_in_im[i] / FFT_POINT_NUM);
+        }
+    }
+
+    return 0;
+}