.define .exg .sect .text .sect .rom .sect .data .sect .bss .sect .text ! Exchange top bytes of stack ! Expects in de-registers the number of bytes to be exchanged. .exg: mov a,e rar cc eoddz !trap if numer of bytes is odd pop h shld .retadr mov h,b mov l,c shld .bcreg lxi h,0 dad sp mov b,h mov c,l !now bc points to first operand dad d !and hl to the second push d !place number of bytes on top of stack 1: mov d,m ldax b mov m,a mov a,d stax b xthl !caused by a lack of registers dcx h !decrement top of stack mov a,h ora l xthl inx h inx b jnz 1b pop d lhld .bcreg mov b,h mov c,l lhld .retadr pchl