《Programming from the Ground Up》阅读笔记：p19-p48

《Programming from the Ground Up》学习第2天，p19-p48总结，总计30页。

一、技术总结

1.object file

p20, An object file is code that is in the machine’s language, but has not been completely put together。

之前在很多地方都看到object file这个概念，但都没有看到起定义，这次终于搞清楚了——object文件就是包含机器语言的文件。

2.汇编语言实现求最大值

#PURPOSE: This program finds the maximum number of a
#         set of data items.

#VARIABLES: The registers have the following uses:
#
# %edi - Holds the index of the data item being examined
# %ebx - Largest data item found
# %eax - Current data item
#
# The following memory locations are used:
#
# data_items - contains the item data. A 0 is used
#              to terminate the data
#
.section .data
data_items:
  .long 3,67,34,222,45,75,54,34,44,33,22,11,66,0

  .section .text

  .global _start
_start:
  movl $0, %edi
  movl data_items(,%edi,4),%eax
  movl %eax, %ebx
start_loop:
  cmpl $0,%eax
  je loop_exit
  incl %edi
  movl data_items(,%edi,4),%eax
  cmpl %ebx, %eax
  jle start_loop

  movl %eax, %ebx
  jmp start_loop
loop_exit:
  movl $1,%eax
  int $0x81

这里作者花了大量的篇幅做解释，但个人觉得在“使用哪种寄存器，为什么使用这种寄存器？”这点上作者没有解释清楚，可能会在后面介绍，先继续往下读。

二、英语总结

1.overwhelm

(1)over-: above, higher in power, above normal…

(2)whelm: turn upside down。

vt. to cause sb to feel strong emotion。

2.diligence

(1)dis-:apart。

(2)*leg-: to collect, gather。

以上两个组合起来的意思是“to pick out, select”， u. the quality of working carefully and with a lot of effort。

3.tinker

vi. to make small change to sth。tinker around with sth和tinker with sth意思一样。

4.process vs processing

A process is a series of steps taken to achieve something, such as the process of making cake.

Gather ingredients
Mix ingredients
Bake
Decorate cake

Processing is when you do things to a substance in order to change it. For example: the processing of oil into gasoline.
process的意思是“步骤”，processing的意思是“处理”。