macros: add min()/max()

macros.h

@@ -0,0 +1,4 @@
+#pragma once
+
+#define min(x, y) ((x < y) ? (x) : (y))
+#define max(x, y) ((x > y) ? (x) : (y))

shell.c

@@ -13,6 +13,7 @@
 #include <limits.h>
 #include <sys/types.h>
 
+#include "macros.h"
 #include "shell.h"
 #include "spi_flash.h"
 #include "usart.h"
@@ -156,7 +157,7 @@ static void do_read(FILE *fp, const char *s)
 		return;
 
 	while (len) {
-		nbytes = (len > 256) ? 256 : len;
+		nbytes = min(len, 256);
 		spi_flash_read(SPI1, addr, buf, nbytes);
 		print_hex_ascii(fp, buf, nbytes);