On Mon, 13 Jun 2016 11:19:06 -0700, Charles Mills wrote: >In the description of LINK in Assembler Services I read > >... > >Does that mean that for standard "old-fashioned" AMODE 31 72-byte savearea >linkage I am obligated to save the high word of R1 before issuing LINK in a >called program? If so, this would seem to be a compatibility issue for older >code that uses LINK. Or is R1 fair game as a work register in a called >program?
The Linkage conventions do not require that R1 be preserved. From the Assembler Services Guide: <quote> Unless otherwise defined by the individual interface, the calling program should expect, upon return, that o The low halves (Bits 32-63) of GPRs 2 through 13 are unchanged o The high halves (Bits 0-31) of GPRs 2 through 14 are unchanged o ARs 2 through 13 are unchanged o FPRs 8 through 15 are unchanged; The Floating Point Control (FPC) Register is unchanged with the exception of two fields: the IEEE exception flags and the data exception code (DXC). o When return information is provided in GPR 0, 1, and/or 15 (for example return and reason codes), only bits 32-63 of the register contain the returned value. </quote> -- Tom Marchant ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
