(r1) CallingCFunction < MecrispCube

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---+ Calling C Functions from Forth and Vice Versa

Procedure Call Standard for the ARM Architecture [[https://developer.arm.com/documentation/ihi0042/j][AAPCS]]

https://community.arm.com/developer/ip-products/processors/b/processors-ip-blog/posts/on-the-aapcs-with-an-application-to-efficient-parameter-passing

| *Register* | *AAPCS Purpose*                                         | *MECRISP Forth Purpose*  | 
| r0         | Argument, result, scratch register 1                    | Scratch                  |
| r1         | Argument, result, scratch register 2                    | Scratch                  |
| r2         | Argument, scratch register 3                            | Scratch                  |
| r3         | Argument, scratch register 4                            | Scratch                  |
| r4         | Variable register 1                                     |                          |
| r5         | Variable register 2                                     |                          |
| r6         | Variable register 3                                     | Top Of Stack TOS         |
| r7         | Variable register 4                                     | Data Stack               |
| r8         | Variable register 5                                     |                          |
| r9         | Platform register (usage defined by platform in use)    |                          |
| r10        | Variable register 7                                     |                          |
| r11        | Variable register 8                                     |                          |
| r12        | Intra-procedure-call scratch register                   |                          |
| r13        | Stack pointer (SP)                                      | Stack pointer (SP)       |
| r14        | Link register (LR)                                      | Link register (LR)       |
| r15        | Program counter (PC)                                    | Program counter (PC)     |



-- %USERSIG{PeterSchmid - 2020-07-13}%

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Topic revision: r1 - 2020-07-13 - PeterSchmid