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Length: 1952 (0x7a0)
Types: TextFile
Notes: UNIX file
Names: »dmul.s«
└─⟦f27320a65⟧ Bits:30001972 Commodore 900 hard disk image with partial source code
└─⟦f4b8d8c84⟧ UNIX V7 Filesystem
└─ ⟦this⟧ »libc/crt/dmul.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 drmul, dlmul .globl SS / double multiply product returned in rq4 / / drmul( da, db) / dlmul( da, &db) / / complexified by lack of unsigned multiply in z8000 drmul: lda rr4, SS|12(r15) jr un, 0f dlmul: ldl rr4, SS|12(r15) 0: sub r15, $16 ldm (rr14), r6, $8 ld r0, SS|20(r15) ld r8, (rr4) ld r1, $32768 ld r3, r1 and r1, r8 xor r8, r1 cp r8, $16 jr lt, retz cp r8, $2047*16 jr ge, retinf and r3, r0 xor r0, r3 cp r0, $16 jr lt, retz cp r0, $2047*16 jr ge, retinf xor r1, r3 ldl rr2, SS|22(r15) ld r6, SS|26(r15) sub r7, r7 ldl rr12, rr4(2) ld r10, rr4(6) sub r11, r11 ldb rl1, $4 0: srl r0 rrc r2 rrc r3 rrc r6 rrc r7 srl r8 rrc r12 rrc r13 rrc r10 rrc r11 dbjnz rl1, 0b setflg C rrc r2 rrc r3 rrc r6 rrc r7 setflg C rrc r12 rrc r13 rrc r10 rrc r11 sub r0, $1022 add r0, r8 jr le, retz / exp will only get smaller cp r0, $2047 jr gt, retinf / by at most 1 srll rr2 / force fractions to be positive rrc r6 rrc r7 srll rr6 srll rr12 rrc r10 rrc r11 srll rr10 multl rq4, rr12 multl rq8, rr2 addl rr4, rr8 subl rr6, rr6 slll rr4 ldl rr10, rr2 multl rq8, rr12 addl rr10, rr4 adc r9, r6 adc r8, r7 slll rr10 / undo effect of adjustment rlc r9 rlc r8 slll rr10 rlc r9 rlc r8 slll rr10 rlc r9 rlc r8 jr c, 0f / justified dec r0 jr le, retz slll rr10 rlc r9 rlc r8 0: cp r0, $2047 jr ge, retinf ldb rl1, $4 / pack result 0: slll rr10 rlc r9 rlc r8 rlc r0 dbjnz rl1, 0b or r0, r1 ld r1, r8 ld r2, r9 ld r3, r10 9: ldm r6, (rr14), $8 add r15, $16 ret retz: subl rr0, rr0 subl rr2, rr2 jr un, 9b retinf: ld r0, $2047*16 or r0, r1 sub r1, r1 subl rr2, rr2 jr un, 9b