From 3350c34a74844e21ea69077e01efff3bae64bdcd Mon Sep 17 00:00:00 2001 From: Kartik Agaram Date: Tue, 23 Mar 2021 17:31:08 -0700 Subject: . --- html/102keyboard.subx.html | 108 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 108 insertions(+) create mode 100644 html/102keyboard.subx.html (limited to 'html/102keyboard.subx.html') diff --git a/html/102keyboard.subx.html b/html/102keyboard.subx.html new file mode 100644 index 00000000..b8f9a64b --- /dev/null +++ b/html/102keyboard.subx.html @@ -0,0 +1,108 @@ + + + + +Mu - 102keyboard.subx + + + + + + + + + + +https://github.com/akkartik/mu/blob/main/102keyboard.subx +
+ 1 # check keyboard for a key
+ 2 # return 0 on no keypress or unrecognized key
+ 3 #
+ 4 # We need to do this in machine code because Mu doesn't have global variables
+ 5 # yet (for the keyboard buffer).
+ 6 
+ 7 == code
+ 8 
+ 9 read-key:  # kbd: (addr keyboard) -> result/eax: byte
+10     # . prologue
+11     55/push-ebp
+12     89/<- %ebp 4/r32/esp
+13     # . save registers
+14     51/push-ecx
+15     # result = 0
+16     b8/copy-to-eax 0/imm32
+17     # ecx = keyboard
+18     8b/-> *(ebp+8) 1/r32/ecx
+19     81 7/subop/compare %ecx 0/imm32
+20     {
+21       75/jump-if-!= break/disp8
+22       # var buffer-byte-addr/ecx: (addr byte)
+23       8b/-> *Keyboard-buffer:read 1/r32/CL
+24       81 0/subop/add %ecx Keyboard-buffer:data/imm32
+25       # var next-key/eax: byte = *buffer-byte-addr
+26       8a/byte-> *ecx 0/r32/AL
+27       # if (next-key != 0) lock and remove from keyboard buffer
+28       81 7/subop/compare %eax 0/imm32
+29       {
+30         74/jump-if-= break/disp8
+31         fa/disable-interrupts
+32         c6 0/subop/copy-byte *ecx 0/imm8
+33         ff 0/subop/increment *Keyboard-buffer:read
+34         81 4/subop/and *Keyboard-buffer:read 0x0f/imm32
+35         fb/enable-interrupts
+36       }
+37       # return
+38       eb $read-key:end/disp8
+39     }
+40     # TODO: fake keyboard
+41 $read-key:end:
+42     # . restore registers
+43     59/pop-to-ecx
+44     # . epilogue
+45     89/<- %esp 5/r32/ebp
+46     5d/pop-to-ebp
+47     c3/return
+
+ + + -- cgit 1.4.1-2-gfad0