diff options
Diffstat (limited to '02')
| -rw-r--r-- | 02/README.md | 3 | ||||
| -rw-r--r-- | 02/in01 | 10 |
2 files changed, 8 insertions, 5 deletions
diff --git a/02/README.md b/02/README.md index 9ba5063..1854baa 100644 --- a/02/README.md +++ b/02/README.md @@ -157,6 +157,9 @@ Numbers cannot appear at the end of a line (this made the compiler simpler to write), so I'm adding a `.` at the end of each one to avoid making that mistake. +The code for `cmp rax, rbx` is now included in all conditional jump instructions +(I kept forgetting to put `cm` before conditional jumps when writing this compiler). + Anything after a command is treated as a comment; additionally `//` can be used for comments on their own lines. I decided to implement this as simply as possible: @@ -42,7 +42,7 @@ the segment we're loading in includes the ELF header at address 0x400000, so we ;im;01;00;00;00;00;00;00;00 write ;sy --- read command (0x400174) -- +-- read a command (0x400174) -- ;im;03;00;00;00;00;00;00;00 input file descriptor ;JA ;im;88;00;40;00;00;00;00;00 where to read to @@ -184,7 +184,7 @@ okay we now have a digit in rbx ;AR ;<I;04 ;+B -;RA store away in rbp +;RA store number away in rbp ;jm;38;ff;ff;ff continue loop unused padding @@ -316,7 +316,7 @@ convert bytes to an offset ;BA offset in rbx -look in the label table +read value from label table ;im;00;00;42;00;00;00;00;00 ;+B ;BA @@ -366,7 +366,7 @@ it's not a label or a number. let's look it up in the instruction table. ;im;d0;0a;40;00;00;00;00;00 start of instruction table ;+B ;BA -;RA store away address of command text in rbp +;RA store away pointer to command text in rbp ;zA;lb ;DA number of bytes to write (used for syscall if command exists) ;BA @@ -388,7 +388,7 @@ bad command! ;00;00;00;00;00;00;00;00;00;00;00;00;00;00;00;00 this is a real command -;BR get address of command text back in rbx +;BR get pointer to command text back in rbx ;im;01;00;00;00;00;00;00;00 add 1 because we don't want to write the length ;+B ;IA address of data to write |