fix readme typos etc

README.md

@@ -25,8 +25,8 @@ whitening/compression step based on [Ascon](https://ascon.iaik.tugraz.at/)-Xofa.
 ## Requirements
 
 * Pico C SDK
-* System must not run from ROSC, and the system clock must be at least 48 MHz
-  (80 MHz or higher preferred, 125 MHz or higher ideal).
+* System must not run from ROSC
+* System clock must be at least 48 MHz (80 MHz or higher preferred, 125 MHz or higher ideal)
 * SysTick not used by something else
 
 ## How it works
@@ -130,9 +130,9 @@ a high enough system clock frequency (≥80 MHz preferred, ≥125 MHz ideal).
 Dieharder isn't the most stringent test suite, though.
 [TestU01](http://simul.iro.umontreal.ca/testu01/tu01.html)'s BigCrush suite is
 much more comprehensive, but requires ***much*** more data (many gigabytes).
-Thanks to the limited throughput of a hardware TRNG, using this test isn't very
+Due to the limited throughput of a hardware TRNG, using this test isn't very
 feasible. Real evaluations such as FIPS 140-2, or Common Criteria EAL4 or
-higher, is completely out of my means.
+higher are completely out of my means.
 
 In conclusion, don't trust someone's life --- neither your own nor someone
 else's --- with this. But otherwise, you should be fine. If you need the
@@ -264,7 +264,8 @@ Preparing to run test 209.  ntuple = 0
         dab_monobit2|  12|  65000000|       1|0.71153312|  PASSED
 ```
 
-At 48 MHz and a core voltage of 0.95 V, there would be three or four `WARN`ings.
+At 48 MHz and a core voltage of 0.95 V, there would be three or four `WARN`ings
+(but still no `FAILED` messages).
 
 ### Throughput
 
@@ -289,9 +290,10 @@ very fast. The "cooked" (whitened) throughput is about 10 times higher than the
   would then modify the ROSC `COUNT` register in parallell. This is bad and
   will lead to bad results. Don't do this. (Or alternatively, add mutex guards,
   or bug me to do so.)
-* **More useful `rand()` functions**: currently, the code just gives you bits,
-  and turning these bits into a random integer in a range, or a random float,
-  ..., is left as an exercise for the reader.
+* **More useful `rand()` functions**: currently, the code just gives you bits.
+  Turning these bits into a random integer in a range, or a random float, ...,
+  is currently left as an exercise for the reader. (Read: I totally forgot
+  about these.)
 * **Protections against physical attacks**: if an adversary is in the physical
   proximity of the device, it's game over. They could attach an SWD debugger to
   the RP2040 (it has no protection against this), use a power side channel or
@@ -314,14 +316,14 @@ Here's a quick example:
 #include "rourand.h" /* 'cooked'/whitened rng */
 
 
-static void health_alarm(const char* msg) {
+static void health_alarm_callback(const char* msg) {
     // TRNG health alarm raised!
     iprintf("TRNG health alarm! %s\n", msg);
 }
 
 int main() {
     /** raw randomness **/
-    enum rourand_error r = rorand_init(health_alarm);
+    enum rourand_error r = rorand_init(health_alarm_callback /* can be NULL */);
     if (r != rr_ok) {
         panic("rorand failed to initialize!");
     }