Misc/abrash-black-book
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Change bold code snippets to inline code blocks

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James Gregory 2013-12-31 17:12:29 +11:00
commit 3c76d884ef
185 changed files with 1772 additions and 1772 deletions
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14
58-03.md
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@ -73,11 +73,11 @@ MOV AH,[BX] ;cycle 1 U-pipe
MOV [DI],AH ;cycle 2 U-pipe
```
The second **MOV**, being dependent on the value loaded into AH by the
first **MOV**, can't execute until the first **MOV** is finished, so the
The second `MOV`, being dependent on the value loaded into AH by the
first `MOV`, can't execute until the first `MOV` is finished, so the
Pentium's second pipe, the V-pipe, lies idle for a cycle. We can reclaim
that cycle simply by shuffling another instruction between the two
**MOV**s.
`MOV`s.
Advancing the destination pointer is easy to speed up: Just build the
offset from one scanline to the next into each pixel-drawing instruction
@ -108,8 +108,8 @@ pointer.*](images/58-04.jpg)
First, we can sum the X and Y integer advance amounts outside the loop,
then add them both to the source pointer with a single instruction.
Second, we can recognize that X advances exactly one extra byte when its
fractional part carries, and use **ADC** to account for X carries, as
shown in Figure 58.5. That single **ADC** can add in not only any X
fractional part carries, and use `ADC` to account for X carries, as
shown in Figure 58.5. That single `ADC` can add in not only any X
carry, but both the X and Y integer advance amounts as well, thereby
eliminating a good chunk of the source-advance code in Listing 58.2.
Furthermore, we should somehow be able to use 32-bit registers and
@ -128,8 +128,8 @@ with bit 15 of EDX always kept at zero; this allows bit 15 to store the
carry status from each Y advance. We can similarly store the fractional
X and Y advance amounts in ECX, and can store the sum of the integer
parts of the X and Y advance amounts in BP. With this arrangement, the
single instruction **ADD EDX,ECX** advances the fractional parts of both
X and Y, and the following instruction **ADC SI,BP** finishes advancing
single instruction `ADD EDX,ECX` advances the fractional parts of both
X and Y, and the following instruction `ADC SI,BP` finishes advancing
the source pointer in X. That's a mere 3 cycles, and all that remains is
to finish advancing the source pointer in Y.