From d98f46ce647846b0aa30b2e16a30fd4e152a1bf5 Mon Sep 17 00:00:00 2001 From: Carlos Maiolino Date: Thu, 10 Jul 2025 22:55:07 +0200 Subject: Add new code Signed-off-by: Carlos Maiolino --- CSAPP/chap2/shifts.c | 39 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 39 insertions(+) create mode 100644 CSAPP/chap2/shifts.c (limited to 'CSAPP/chap2/shifts.c') diff --git a/CSAPP/chap2/shifts.c b/CSAPP/chap2/shifts.c new file mode 100644 index 0000000..836476d --- /dev/null +++ b/CSAPP/chap2/shifts.c @@ -0,0 +1,39 @@ +/* + * Shift operations + * + * Right shifts might use either arithmetic shifts or logical shifts. + * + * This small piece of code should identify which one is used + */ + +#include + +int main(void) +{ + /* Using char so we care for a single byte only */ + char x, a; + unsigned char y, b; + /* bin 10101001 */ + a = b = 0xA9; + + printf("Original signed variable: 0x%.2x\n", a); + + /* + * Signed data variables are right shifted using Arithmetic shift. i.e. + * left bits are filled with a copy of the most significant bit of the + * original value + */ + x = a >> 3; + printf("Signed right shift by 3: 0x%.2x\n\n", x); + + printf("Original unsigned variable: 0x%.2x\n", b); + /* + * Unsigned data variables are right shifted logically. i.e. left bits + * are just filled with zeros + */ + y = b >> 3; + printf("Unsigned right shift by 3: 0x%.2x\n", y); + return 0; +} + + -- cgit v1.2.3