CS61C

C

• printf:
  • %s means print a string
  • %d means print a decimal number
  • %X means print a hexadecimal number
• ^ bitwise XOR
• 取反最低位 X^1 注意不是 ~X
• C Macro: "Find and replace"
• typedef A B def B as A
• int32_t means 32 bits, and 4 bytes
• Endianness and Alignment
  • Endianness: little endian
  • Alignment
• Address Space
  • passing pointers caller to callee is ok, but never callee to caller.
• realloc(void* ptr, size_t size) returns new address of block.(in heap)
  • realloc(NULL, size); behaves like malloc
  • realloc(ptr,0); behaves like free

**
//Safer
TYPE *tmp = realloc(ptr, NEW_SIZE);
if (tmp) { ptr = tmp; }

• valgrind
• Function Pointers
• dereference: access the data/value in the memory.
• Generic Pointers
• void *end = (char *) arr + (nelems-1) * nbytes, (char *) means that convert arr from void*(have defined that) to char*
• dereference a variable that is not a pointer--C will treat theat variable's underlying bits as if they were a pointer
• 字符串使用双引号而不是单引号。

RISC-V

• R-TYPE
• I-TYPE I*(shift instructions)
• S-TYPE
• U-TYPE
• B-TYPE
• J-TYPE n
  

注意

• load 是 load 某寄存器中存储的对应的地址（中的值）类似，而add是处理存储器中存储的值。
• jal 保存返回值，j 不保存返回值。

Compiler,Assembler,Linker,Loader

• Compilation: what it actually means (and discovered it's just the first step in a very long process)
• Assembly: how human-readable parts of assembly code get swapped out for more machine-readable features
• Linking: how different files and libraries make their way into the final product
• Loading: how a system processes our code to run

数电