Initial commit of files related to NED architecture.

[ned1] / software / assembly_fragments / subroutines / sr_terminalIO.asm

putchar
# Description:
#   Writes one character to the terminal.
# Stack Requirements:
#   Character to write
#   Return PC <-- TOS
   WORD_134217728      # XBUF
   WORD_134217732      # XCSR
   LDSP+3
   SWAP
putcharloop
   LDSP+0
   LOAD
   TEST
   BRZ>putcharloop
   TEST # Drop XCSR from stack
   SWAP
   STORE
   # Wrote the character. Clean up stack and return.
   STSP+0
   RTS

getchar
# Description:
#   Reads one character from the terminal.
# Stack Requirements:
#   Return PC <-- TOS
   WORD_134217736      # RBUF
   WORD_134217740      # RCSR
getcharloop
   LDSP+0
   LOAD
   TEST
   BRZ>getcharloop
   LDSP+1
   LOAD
   # Found a character. Clean up stack and return.
   STSP+0
   STSP+0
   SWAP
   RTS