Rather than using a loop to calculate the interrupt vector, use the ctlz instruction.
diff --git a/system/alpha/palcode/platform_m5.s b/system/alpha/palcode/platform_m5.s
index 7e068b1..9012fd7 100644
--- a/system/alpha/palcode/platform_m5.s
+++ b/system/alpha/palcode/platform_m5.s
@@ -839,39 +839,22 @@
bis r8,r9,r8
ldqp r9,0x0020(r8) // read PIC1 ISR for interrupting dev
-#if 0 // we have a 21164 so this won't work because of the ctlz, if we ever change that...
normal_int:
- ctlz r9,r10 // count the number of leading zeros
+ //ctlz r9,r10 // count the number of leading zeros
+ // EV5 doesn't have ctlz, but we do, so lets use it
+ .byte 0x4a
+ .byte 0x06
+ .byte 0xe9
+ .byte 0x73
lda r11,63(r31)
subq r11,r10,r17 // subtract from
lda r9,0x10(r31)
mulq r17,r9,r17 // compute 0x900 + (0x10 * Highest DIRn-bit)
- lda r9,0x900(r31)
- addq r17,r9,r17
-
- br r31, pal_post_interrupt
-#endif
-
-normal_int:
- or r31,63,r17 // load 63 into the counter
- or r31,1,r11
- sll r11,63,r11 // load a 1 into the msb
-
-find_msb:
- and r9,r11,r10
- bne r10, found_msb
- srl r11,1,r11
- subl r17,1,r17
- br r31, find_msb
-
-found_msb:
- lda r9,0x10(r31)
- mulq r17,r9,r17 // compute offset + (0x10 * Highest DIRn-bit)
addq r17,r13,r17
br r31, pal_post_interrupt
-
+
ALIGN_BRANCH
pal_post_dev_interrupt:
or r13, r31, r17 // move vector to a1
