ack/mach/mips/libem/set.s

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#
.sect .text; .sect .rom; .sect .data; .sect .bss
/*
* Create singleton set.
* Stack: ( bitnumber size -- set )
*/
.sect .text
.define .set
.set:
lw r4, 0(sp) ! r4 = size
lw r5, 4(sp) ! r5 = bit number
addiu sp, sp, 8
srl r4, r4, 2 ! r4 = word count
! Create an empty set by pushing zeros.
1:
addiu sp, sp, -4
sw zero, 0(sp)
addiu r4, r4, -1
bne r4, zero, 1b
nop
! sp now points at the set.
andi r6, r5, ~31 ! r6 = bit offset of base of word in set
srl r6,r6, 3 ! r6 = byte offset of word in set
addu r6, sp, r6 ! r6 = address of word in set
andi r7, r5, 31 ! r7 = bit number within word
li r8, 1
sllv r8, r8, r7 ! r8 = word with 1 set
sw r8, 0(r6) ! write to set
jr ra
nop