Maxim-integrated MAXQ622 Manual do Utilizador descarregar pdf (Página 41)

MAXQ612/MAXQ622 User’s Guide

Maxim Integrated 3-5

3.3.4 Moving Values Between Registers of Different Sizes

Before covering some transfer scenarios that might arise, a special register must be introduced that is used in many

of these cases. The 16-bit general register (GR) is expressly provided for performing byte singulation of 16-bit words.

The high and low bytes of GR are individually accessible in the GRH and GRL registers, respectively. A read-only GRS

GRL.

3.3.5 8-Bit Destination ← Low Byte (16-Bit Source)

The simplest transfer possibility would be loading an 8-bit register with the low byte of a 16-bit register. This transfer

does not require use of GR and requires a prefix only if the destination or source register are outside the single-cycle

write or read regions, 0 to 7h and 0 to 0Fh, respectively.

move OFFS, LC[0] ; copy the low byte of LC[0] to the OFFS

; register

move ULDR, @DP[1] ; copy the low byte @DP[1] to the ULDR register

move WDCN, LC[0] ; assembles to: move PFX[2], #00h

; move (WDCON-80h), LC[0]

3.3.6 8-Bit Destination ← High Byte (16-Bit Source)

If, however, we needed to load an 8-bit register with the high byte of a 16-bit source, it would be best to use the GR

move GR, LC[0] ; move LC[0] to the GR register

move IC, GRH ; copy the high byte into the IC register

3.3.7 16-Bit Destination ← Concatenation (8-Bit Source, 8-Bit Source)

Two 8-bit source registers can be concatenated and stored into a 16-bit destination by using the prefix register to hold

the high-order byte for the concatenated transfer. An additional cycle could be required if either source byte register

index is greater than 0Fh or the 16-bit destination is greater than 07h.

move PFX[0], IC ; load high order source byte IC into PFX

move @++SP, AP ; store @DP[0] the concatenation of IC:AP

; 16-bit destination sub-index: dst=08h

; 8-bit source sub-indexes:

; high=10h, low=11h

move PFX[1], #00h ;

move PFX[3], hig ; PFX=00:high

move dst, low ; dst=high:low

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Maxim-integrated MAXQ622 Manual do Utilizador Página 41