48 lines
948 B
ArmAsm
48 lines
948 B
ArmAsm
#
|
|
.sect .text; .sect .rom; .sect .data; .sect .bss
|
|
|
|
/* this is not a subroutine, but just a
|
|
* piece of code that computes the jump-
|
|
* address and jumps to it.
|
|
* traps if resulting address is zero
|
|
*
|
|
* Stack: ( value tableaddr -- )
|
|
*/
|
|
|
|
.sect .text
|
|
.define .csb
|
|
.csb:
|
|
lw r4, 0(sp) ! r4 = address of table
|
|
lw r5, 0(sp) ! r5 = value
|
|
addiu sp, sp, 8
|
|
|
|
lw r6, 0(r4) ! r6 = default target
|
|
lw r7, 4(r4) ! r7 = table count
|
|
|
|
2:
|
|
addiu r7, r7, -1 ! decrement count
|
|
bltz r7, 1f ! exit loop if out
|
|
nop
|
|
|
|
lw r8, 8(r4) ! candidate value
|
|
beq r8, r5, 3f ! branch if equal
|
|
nop
|
|
|
|
addiu r4, r4, 8 ! next entry
|
|
b 2b
|
|
nop
|
|
|
|
3:
|
|
/* We found an item in the table. */
|
|
lw r6, 12(r4) ! load jump target
|
|
/* fall through */
|
|
1:
|
|
beq r6, zero, 4f /* trap if null */
|
|
nop
|
|
jr r6 /* otherwise jump */
|
|
nop
|
|
4:
|
|
j .trap_ecase
|
|
nop
|
|
|