examples/natmod/deepcraft: Add math functions.

Signed-off-by: NikhitaR-IFX <[email protected]>

Author: NikhitaR-IFX

examples/natmod/deepcraft/dc_mp_iface.c

@@ -7,6 +7,112 @@ void *memcpy(void *dst, const void *src, size_t n) {
 void *memset(void *s, int c, size_t n) {
     return mp_fun_table.memset_(s, c, n);
 }
+
+// =============================================================================
+// libm shims — safe replacements for arm-none-eabi Newlib math functions.
+//
+// libm.a is NOT linked (LIBM_PATH := in Makefile) because mpy_ld cannot
+// resolve libm's internal Newlib dependencies (__errno, _REENT, kernel
+// helpers).  Calling an unresolved libm symbol causes a silent HardFault.
+//
+// These shims use only integer ops and IEEE 754 bit manipulation — no
+// external dependencies.  They cover all single-precision functions
+// commonly used by DEEPCRAFT / TensorFlow Lite inference models.
+//
+// If a future model needs a function not listed here, the build will fail
+// with a clear "undefined symbol" link error.
+// =============================================================================
+
+// Helper: bit-cast float - unsigned int without UB
+static inline unsigned int _f2u(float f) { union { float f; unsigned int u; } v; v.f = f; return v.u; }
+static inline float _u2f(unsigned int u) { union { float f; unsigned int u; } v; v.u = u; return v.f; }
+
+// --- expf ---
+// Degree-5 minimax polynomial + IEEE 754 exponent scaling.
+// Max error ~1.5 ULP for |x| <= 88.
+float expf(float x) {
+    if (x > 88.0f)  return 3.40282347e+38f;
+    if (x < -88.0f) return 0.0f;
+    int n = (int)(x * 1.4426950409f + (x >= 0.0f ? 0.5f : -0.5f));
+    float r = x - (float)n * 0.6931471806f;
+    float p = 1.0f + r * (1.0f + r * (0.5f + r * (0.16666667f +
+              r * (0.041666667f + r * 0.0083333333f))));
+    return p * _u2f((unsigned int)((n + 127) << 23));
+}
+
+// --- logf ---
+// Natural log via exponent extraction + polynomial on [sqrt(0.5), sqrt(2)].
+float logf(float x) {
+    if (x <= 0.0f) return -3.40282347e+38f;
+    int e = (int)((_f2u(x) >> 23) & 0xFF) - 127;
+    float m = _u2f((_f2u(x) & 0x007FFFFFu) | 0x3F000000u); // m in [0.5, 1)
+    if (m < 0.70710678f) { m *= 2.0f; e -= 1; }
+    float f = (m - 1.0f) / (m + 1.0f), f2 = f * f;
+    float p = f * (2.0f + f2 * (0.66666667f + f2 * (0.4f + f2 *
+              (0.28571429f + f2 * 0.22222222f))));
+    return p + (float)e * 0.6931471806f;
+}
+
+// --- log2f ---
+float log2f(float x) { return logf(x) * 1.4426950409f; }
+
+// --- log10f ---
+float log10f(float x) { return logf(x) * 0.4342944819f; }
+
+// --- tanhf ---
+// tanh(x) = (e^2x - 1)/(e^2x + 1); clamped for |x| > 9 (result = ±1).
+float tanhf(float x) {
+    if (x >  9.0f) return  1.0f;
+    if (x < -9.0f) return -1.0f;
+    float e2x = expf(2.0f * x);
+    return (e2x - 1.0f) / (e2x + 1.0f);
+}
+
+// --- sqrtf ---
+// Three Newton-Raphson iterations on an IEEE 754 seed estimate (~6 correct bits).
+// On Cortex-M4F the compiler may emit vsqrt.f32 directly and never call this.
+float sqrtf(float x) {
+    if (x <= 0.0f) return 0.0f;
+    float r = _u2f(0x1fbb4000u + (_f2u(x) >> 1)); // seed: ~half the exponent
+    r = 0.5f * (r + x / r);
+    r = 0.5f * (r + x / r);
+    r = 0.5f * (r + x / r);
+    return r;
+}
+
+// --- fabsf --- (often compiled to vabs.f32 inline, but shim for safety)
+float fabsf(float x) { return _u2f(_f2u(x) & 0x7FFFFFFFu); }
+
+// --- floorf ---
+float floorf(float x) { int i = (int)x; return (float)(i - (x < (float)i)); }
+
+// --- ceilf ---
+float ceilf(float x) { int i = (int)x; return (float)(i + (x > (float)i)); }
+
+// --- roundf ---
+float roundf(float x) { return (x >= 0.0f) ? floorf(x + 0.5f) : ceilf(x - 0.5f); }
+
+// --- fmodf ---
+float fmodf(float x, float y) {
+    if (y == 0.0f) return 0.0f;
+    float q = x / y;
+    int n = (int)q;
+    return x - (float)n * y;
+}
+
+// --- powf ---
+// a^b = exp(b * ln(a)); handles integer-exponent cases first for accuracy.
+float powf(float a, float b) {
+    if (b == 0.0f) return 1.0f;
+    if (a == 0.0f) return 0.0f;
+    if (a < 0.0f) {
+        int ib = (int)b;
+        if ((float)ib != b) return 0.0f; // non-integer exponent of negative base
+        return (ib & 1) ? -expf(b * logf(-a)) : expf(b * logf(-a));
+    }
+    return expf(b * logf(a));
+}
+
 #endif
 
 int native_errno=0;
@@ -37,7 +143,7 @@ static mp_obj_t dc_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_k
 mp_obj_t mpy_init(mp_obj_fun_bc_t *self, size_t n_args, size_t n_kw, mp_obj_t *args) {
     // This must be first, it sets up the globals dict and other things
     MP_DYNRUNTIME_INIT_ENTRY
-    
+
     // Populate type
     dc_type.base.type = (void*)&mp_type_type;
     dc_type.flags = MP_TYPE_FLAG_NONE;
@@ -57,4 +163,4 @@ mp_obj_t mpy_init(mp_obj_fun_bc_t *self, size_t n_args, size_t n_kw, mp_obj_t *a
     // This must be last, it restores the globals dict
     MP_DYNRUNTIME_INIT_EXIT
 
-}
+}

examples/natmod/deepcraft/mp_src.c

@@ -30,24 +30,24 @@ mp_obj_t init(mp_obj_t self_in){
 
 mp_obj_t enqueue(mp_obj_t self_in, const mp_obj_t data_in_obj){
     dc_obj_t *self = MP_OBJ_TO_PTR(self_in);
-    
+
     // Check if model is initialized
     if(!self->model_state){
-        mp_raise_ValueError("Model should be initialized first.");
+        mp_raise_ValueError(MP_ERROR_TEXT("Model should be initialized first."));
     }
 
-    float data_in[self->model_in_dim];
-    mp_obj_t *data_in_items;
-    size_t len;
-    mp_obj_get_array(data_in_obj, &len, &data_in_items);
+    // Use buffer protocol (array.array('f', ...)) instead of mp_obj_get_float to avoid
+    // mp_fun_table ABI mismatch issues.
+    // This is the same approach used by dequeue() and avoids float extraction entirely.
+    mp_buffer_info_t buf_info;
+    mp_get_buffer(data_in_obj, &buf_info, MP_BUFFER_READ);
+    float *data_in = (float *)buf_info.buf;
+    size_t len = buf_info.len / sizeof(float);
 
     if (len != self->model_in_dim) {
-        mp_raise_ValueError("data_in must be a list of floats with size matching to input dimensions to model. Check using get_model_input_dim().");
+        mp_raise_ValueError(MP_ERROR_TEXT("data_in must be array.array('f', ...) with length matching model input dimensions."));
     }
 
-    for (int i = 0; i < self->model_in_dim; i++) {
-        data_in[i] = mp_obj_get_float(data_in_items[i]);
-    }
     int result = IMAI_enqueue(data_in);
     return MP_OBJ_NEW_SMALL_INT(result);
 }
@@ -100,4 +100,4 @@ static const mp_obj_fun_builtin_fixed_t get_model_input_dim_obj = {
 static const mp_obj_fun_builtin_fixed_t get_model_output_dim_obj = {
     .base = { &mp_type_fun_builtin_1 },
     .fun._1 = (mp_fun_1_t)get_model_output_dim,
-};
+};