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Length: 2047 (0x7ff)
Types: TextFile
Notes: UNIX file
Names: »dadd.s«
└─⟦f27320a65⟧ Bits:30001972 Commodore 900 hard disk image with partial source code
└─⟦f4b8d8c84⟧ UNIX V7 Filesystem
└─ ⟦this⟧ »libc/crt/dadd.s«
/ floating point package for segmented z-8001 / timothy s. murphy 10/84 / IEEE format / double: 63 62 52 51 0 / sign bin exp +1022 fraction (missing hi bit) / float: 31 30 23 22 0 / sign bin exp +126 fraction (missing hi bit) / .globl dradd, dladd, drsub, dlsub / add, subtract doubles return result a+b or a-b in rq0 / / dradd( da, db) / dladd( da, &db) / drsub( da, db) / dlsub( da, &db) .globl SS dradd: sub r1, r1 lda rr4, SS|12(r15) jr un, 0f dladd: sub r1, r1 ldl rr4, SS|12(r15) jr un, 0f drsub: ld r1, $32768 lda rr4, SS|12(r15) jr un, 0f dlsub: ld r1, $32768 ldl rr4, SS|12(r15) 0: sub r15, $16 ldm (rr14), r6, $8 ldl rr6, SS|20(r15) ldl rr8, SS|24(r15) ldl rr10, (rr4) xor r10, r1 ldl rr12, rr4(4) ldl rr0, $0x80008000 / extract signs and r1, r6 xor r6, r1 and r0, r10 xor r10, r0 ldb rl1, rh0 cpl rr6, rr10 jr ugt, 0f jr ult, 1f cpl rr8, rr12 jr uge, 0f 1: exb rh1, rl1 ex r6, r10 ex r7, r11 ex r8, r12 ex r9, r13 0: ldl rr2, $0x7ff07ff0 / extract exponents and r2, r6 jr z, retz cp r2, $2047*16 jr ge, retinf ld r0, r2 / will be result exp xor r6, r2 and r3, r10 jr z, 8f xor r10, r3 set r6, $4 / implicit bits set r10, $4 sub r2, r3 jr z, 0f / exps agree so no alignment srl r2, $4 cp r2, $52 jr ge, 8f / too small - ret larger operand 1: srll r10 rrc r12 rrc r13 djnz r2, 1b 0: cpb rh1, rl1 jr eq, 0f / signs agree - do add subl rr8, rr12 / else sub sbc r7, r11 sbc r6, r10 / any underflow is possible jr nz, 1f test r7 jr nz, 1f testl rr8 jr nz, 1f retz: subl rr0, rr0 subl rr2, rr2 jr un, 9f 2: dec r0, $16 jr le, retz slll rr8 rlc r7 rlc r6 1: bit r6, $4 jr z, 2b jr un, 8f 0: addl rr8, rr12 adc r7, r11 adc r6, r10 bit r6, $5 jr z, 8f inc r0, $16 cp r0, $2047*16 jr lt, 0f retinf: ld r0, $2047*16 orb rh0, rh1 sub r1, r1 subl rr2, rr2 jr un, 9f 0: srll rr6 rrc r8 rrc r9 8: orb rh0, rh1 res r6, $4 or r0, r6 ld r1, r7 ldl rr2, rr8 9: ldm r6, (rr14), $8 inc r15, $16 ret