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/*
* startsf.s
*
* Common preamble for floating point routines that take two operands
* Common epilogue for floating point routines that take two operands
*
* The contents of this file are subject to the Mozilla Public License
* Version 1.0 (the "License"); you may not use this file except in
* compliance with the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS"
* basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the
* License for the specific language governing rights and limitations
* under the License.
*
* The Original Code is Librcx floating point code, released May 27, 1999.
*
* The Initial Developer of the Original Code is Kekoa Proudfoot.
* Portions created by Kekoa Proudfoot are Copyright (C) 1999
* Kekoa Proudfoot. All Rights Reserved.
*
* Contributor(s): Kekoa Proudfoot <kekoa@graphics.stanford.edu>
*/
.section .text
;;
;; function: startsf
;; input: float in r0r1 and float at caller's sp+2 before call
;; output: first float in r0r1 and second float at caller's sp+16 after call
;; expanded first float, r3 flags/sign, r4 exponent, r5r6 mantissa
;; expanded second float, sp+0 exponent, sp+2 flags/sign, sp+4 mantissa
;; expanded second float flags/sign also in r2
;; saved r4, r5, r6 at caller's sp+12, sp+10, sp+8
;;
.global ___startsf
___startsf:
; Assume r2 and r3 saved by original caller
pop r2 ; load return address to r2
; Save registers on stack
push r4
push r5
push r6
; Expand the second operand
mov.w @(8,r7),r5 ; copy second operand (sp+8) to r5r6
mov.w @(10,r7),r6
jsr ___expandsf ; expand to r3h r3l r4 r5r6
; Save expanded second operand to stack by pushing in reverse order
push r6 ; mantissa lower word
push r5 ; mantissa upper word
push r3 ; flags, sign
push r4 ; exponent
; At this point, stack looks like caller will see it:
; sp+0 - second operand exponent
; sp+2 - second operand flags
; sp+3 - second operand sign
; sp+4 - second operand mantissa
; sp+8 - saved r6
; sp+10 - saved r5
; sp+12 - saved r4
; sp+14 - caller's return address
; sp+16 - second operand
; Put our return address back on stack
push r2
; Copy second operand flags/sign to r2
mov.w r3,r2
; Expand the first operand
mov.w r0,r5 ; copy first operand to r5r6
mov.w r1,r6
jsr ___expandsf ; expand to r3h r3l r4 r5r6
; Return
rts
;;
;; entry point: finishsf
;; input: return value in r0r1
;; output: cleans up stack, restoring r4 r5 r6 and leaving r0r1 intact
;;
.global ___finishsf
___finishsf:
; Deallocate stack space
add.b #8,r7l
addx.b #0,r7h
; Restore registers
pop r6
pop r5
pop r4
; Return for caller
rts
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