Commit 549e1f4f authored by Richard Buckley's avatar Richard Buckley
Browse files

Added asm files from SupportLib.

parent 200ba0fe
a1 RN 0
a2 RN 1
a3 RN 2
a4 RN 3
v1 RN 4
v2 RN 5
ip RN 12
sp RN 13
lr RN 14
pc RN 15
EXPORT muldiv
;;;; IMPORT raise
; muldiv(a, b, c)
; result = a*b/c
; the intermediate product is 64 bits long
; do everything using moduluses, and sort out signs later
STMFD sp!, {a1, a2, a3, a4, v1, v2, lr}
; first, the double-length product, returned in a3 & a4
; uses ip, a1 and a2 as workspace
MOV a3, #0
MOV a4, #0
MOV ip, #0
CMPS a2, #0
RSBLT a2, a2, #0 ; abs b
MOV v2, a2
CMPS a1, #0
RSBLT a1, a1, #0 ; abs a
MOVS a2, a2, LSR #1
BCC muldiv1
ADDS a4, a4, a1
ADC a3, a3, ip
MOVS a1, a1, ASL #1
ADC ip, ip, ip
CMPS a2, #0
BNE muldiv0
; now the 64*32 bit divide
; dividend in a3 and a4
; remainder ends up in a4; quotient in ip
; uses a1 and a2 to hold the (shifted) divisor;
; v1 for the current bit in the quotient
LDR a2, [sp, #8] ; recover divisor
CMPS a2, #0
LDMEQFD sp!, {a1-a4, v1, v2, pc}^
;;was BEQ muldiv_by_0, but we might be a module
RSBLT a2, a2, #0 ; abs c
MOV v2, a2
MOV ip, #0
MOV a1, #0
MOV v1, #0
MOV lr, #1
CMPS a1, #&80000000
BCS muldiv3
CMPS a1, a3
CMPEQS a2, a4 ; compare of [a1, a2] against [a3, a4]
BCS muldiv3
MOVS a2, a2, ASL #1
MOV a1, a1, ASL #1
ADC a1, a1, #0
ADD v1, v1, #1
B muldiv2
CMPS a1, a3
CMPEQS a2, a4
BHI muldiv4
CMPS v1, #31
ADDLE ip, ip, lr, ASL v1
SUBS a4, a4, a2
SBC a3, a3, a1
MOVS a1, a1, ASR #1
MOV a2, a2, RRX
SUBS v1, v1, #1
BGE muldiv3
; now all we need to do is sort out the signs.
LDMFD sp!, {a1, a2, a3, v1}
EOR a2, a2, a1 ; a2 has the sign of a*b: a3 is the sign of c
MOV a1, ip
TEQS a2, a3 ; if a*b and c have opposite signs,
RSBMI a1, a1, #0 ; negate the quotient
CMPS a2, #0 ; and if the dividend was negative,
RSBLT a4, a4, #0 ; negate the remainder
;;;; Now discard the remainder - J R C 19 March 1991
;;;; STR a4, [v1]
LDMFD sp!, {v1, v2, pc}^
muldiv_by_0 ;not used
;;;; LDMFD sp!, {a1-a4, v1, v2, lr}
;;;; MOV a1, #2 ; SIGFPE
;;;; B raise
;riscosa.asm - length of a variable
;written by Jonathan Coxhead, 15th Aug 1995
EXPORT riscos_var_len
riscos_var_len ROUT
;Entry R0 -> name of a variable
; R1 = variable type (os_VARTYPE_EXPANDED or 0)
;Exit R0 = length of variable value, or -1 if not found
MOV R4, R1
MOV R3, #0
MOV R2, #1 << 31
MOV R1, #Null
SWI XOS_ReadVarVal
;Ignore error
MVN R0, R2
LDMFD SP!, {R4, PC}^
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