feat(ulp-riscv): Add convenience print function that supports different widths

This commit adds a convenience function to print hex numbers of
different widths on the ULP RISC-V core.

Closes https://github.com/espressif/esp-idf/pull/13180

components/ulp/ulp_riscv/ulp_core/include/ulp_riscv_print.h

@@ -35,6 +35,14 @@ void ulp_riscv_print_str(const char *str);
  */
 void ulp_riscv_print_hex(int h);
 
+/**
+ * @brief Prints a hex number with the specified number of digits. Does not print 0x, only the digits
+ *
+ * @param Hex number to print
+ * @param number_of_digits Number of digits to print.
+ */
+void ulp_riscv_print_hex_with_number_of_digits(int h, int number_of_digits);
+
 #ifdef __cplusplus
 }
 #endif

components/ulp/ulp_riscv/ulp_core/ulp_riscv_print.c

@@ -60,3 +60,38 @@ void ulp_riscv_print_hex(int h)
 
     ULP_RISCV_EXIT_CRITICAL();
 }
+
+void ulp_riscv_print_hex_with_number_of_digits(int h, int number_of_digits)
+{
+    int x;
+    int c;
+
+    if (!s_print_ctx.putc) {
+        return;
+    }
+
+    if (number_of_digits < 1) {
+        return;
+    }
+
+    if (number_of_digits >= 8) {
+        ulp_riscv_print_hex(h);
+        return;
+    }
+
+    /* Perform the bit-banged UART operation in a critical section */
+    ULP_RISCV_ENTER_CRITICAL();
+
+    // Does not print '0x', only the digits specified by the number_of_digits argument
+    for (x = 0; x < number_of_digits; x++) {
+        c = (h >> ((number_of_digits - 1) * 4)) & 0xf; // extract the leftmost byte
+        if (c < 10) {
+            s_print_ctx.putc(s_print_ctx.putc_ctx, '0' + c);
+        } else {
+            s_print_ctx.putc(s_print_ctx.putc_ctx, 'a' + c - 10);
+        }
+        h <<= 4; // move the 2nd leftmost byte to the left, to be extracted next
+    }
+
+    ULP_RISCV_EXIT_CRITICAL();
+}